First thing is first, yes, the Steam version of the game does not come stock with Ferrari or Porsche cars. This is a licensing issue and Steam is not trying to screw you over. However, you can easily return Ferrari and Porsches to your game by updating it and installing the No-CD patch (Note: Steam version is already No CD, you still need the patch though to get Ferrari and Porsche to work).

On to the game. It's a very old game, true, but the physics are outstanding and with mod added content like cars and tracks you'll find the graphical experience to be pleasant enough to not be distracting and when you're in the moment it's very easy to forget how dated the game looks. The AI is like all AI: terrible. They can run real life lap times and generally speaking they're fairly competent -but- they are absolutely terrible at racing off the racing line. This isn't unique to GTR2 or the GMotor engine, it's an industry wide issue. It's AI, you deal with it, and it's not too bad at the end of the day.

Other things to note:
1. The FFB is amazing once tuned properly for your wheel. It's horrible if it's tuned wrong. Take some time to set it up right.
2. If you're using a controller, you'll find that the game is just as enjoyable and just as playable
3. If you're using a keyboard, you can STILL be competitive with the right sensitivity adjustments. The game is that versatile, but obviously your experience will be the best with a wheel.
4. The 24H day/night cycle works as intended and is gorgeous. Sunsets blind, nights are dark.
5. The weather system leaves something to be desired. There is no dynamic weather to speak of, though there is a mod that corrects this. When the tracks are wet it's more like ice and more often than not TCS isn't enough.

6. Most importantly, this game has a STRONG modding community. Is there a major track out there you want in your game? Someone has created it. Is there a series you want to race in? Someone has created it. The only major series absent to my knowledge are the latest models of NASCAR, but this is a road racing game so what do you expect?

EDIT:
I figured I should also mention how it compares to other games. The next generation of sims is coming out as we speak so it might seem weird to pick up an 8 year old game. I feel that Assetto Corsa is likely going to be GTR2's spiritual replacement (Not that I have anything against pCars, or that there is anything wrong with pCars) in terms of the "sim" quality and possibly modding community. But it isn't there yet.

As it stands this is IMO, the best sim out there that you can buy overall, and it's largely thanks to the modding community. If you don't feel comfortable modding, then it's still a great sim with the 2004 GT championship, but I would advise picking up AC or pCars instead (once they release in full that is). The maturity of the mod community is what makes GTR2 what it is today, because they've pushed the Gmotor engine to its limits. Being said, AC looks better, handles better, and has arguably better FFB. It's too early to say how the career mod, modability, and AI are in comparison.

If you're comfortable modding, then this is and will continue to be the best sim out there until either AC, pCars, or rfactor2 builds up its mod community. If so, buy the game and head over to nogripracing.com and see what I'm talking about.

I've ran the championships a run once, currently working on my second run-through of the game. The time I've clocked in this game is closer to 40-ish hours than the 24 it says; the game launches a launcher (for file permissions) before it launches and when the launcher closes, Steam no longer says I'm in-game.

ANYWAY. Right, review time.

PROS

- GRAPHICS. For a game made almost 9 years ago, the graphics hold up well. Vehicle liveries are clear and easy to read, cockpit decals are clear, and you can read the speed off your in-dash display. (All this, of course, can be downscaled, or in the case of the in-dash display, completely turned off.)

- REALISTIC DAMAGE. Run your engine too hard and it'll blow out. Hit a wall wrong and your splitter may come off which will make your vehicle tend to understeer, or you might have a blowout which will cause the vehicle to pull to that side. Your engine may even catch fire if you're running it at too much throttle. (This can be turned off.)

- TUNING. You can tune the cars almost how you'd like (within reason, of course!) and the minor differences in tuning can be felt on the track. The game includes native support for MoTeC, a powerful tool used in real-world motorsport, to be used for track data acquisition. (Sadly, the MoTeC acquisition is not live - you can't have it on one monitor and showing live changes in speed, steering wheel angle, etc.) Note that MoTeC is not included with the game, and you should either be familiar with the tool or search for a GTR2 worksheet, as well as how to use the data in tuning your vehicle before it will be useful to you at all.

- GOOD AI. Most of the AI will follow a realistic racing line, including when passing a wreck under yellow, overtaking or allowing someone to overtake, or recovering from a wreck. You can even adjust how strongly the AI performs (I believe it goes 75% strength to 125%?) as well as how their racing style is (Timid, Clean, Realistic, Aggressive, Psychotic I believe the choices are).

- DAY/NIGHT CYCLE. This is surprisingly one of the things I like most about GTR2. The game includes a day/night cycle which you can adjust the speed on in the menus. It goes from realtime (24 hours == 24 hours) all the way to 60× (24 minutes == 24 hours) and the opponent vehicles will turn their headlights on at dusk and off at dawn.

- WEATHER EFFECTS. This isn't as surprising considering many modern games have it, but remember: this was made in 2006. It comes with basic rain effects (road mist, rain fall, rain splash on windscreen) and rain strongly affects traction in 4 stages, shown by the track condition with increasing amount of traction loss: Dry, damp, wet, and flooded. You also have 3 different types of tyres: Slicks (with 3 degrees of compound softness), intermediates, and wet tyres (with 2 degrees of compound softness).

- MODDING. The game makes itself easy to mod. Want a new livery for that car you've been eyeing? Go online, find a template and make one. You don't even need to place it in GTR2's archive files if you don't want to, the game will load loose files. You can add custom music as well (note: it plays in order of filename, 0-9 then A-Z).

All-in-all the bits above are what make the game great.

CONS

- PROGRESSION. While this isn't a bad thing in itself, the way it pulls it off leaves a lot to be desired, and could have been worked much better. In order to unlock tracks, you need to win different championships (under the CUSTOM tab in the championships menu) and in order to unlock the different championships, you need to - of all things - get the gold awards in the driving school levels. NOTE: This can be bypassed by placing a blank file titled SDNDTG.DYN in the root GTR2 folder.

- NOT UPDATED. There is an updated patch of the game which solves some issues, such as Hockenheimring's AI not turning off their pitlane speed limiter after exiting pitlane, which was not released on Steam. The version you get is incompatible with versions using the most updated version, unless you manually patch the game.

- NOT ALL CARS INCLUDED. Ferraris and Porsches are included with the game, however due to the Steam game's design you would need to manually do some stuff to the files in order to drive them - I'd go into detail but it's not permitted by the Guidelines, so if you must know, you can search it. If you do NOT do this, some championships are cut from the game, and any Porsche or Ferrari you see will be from a manufacturer titled "Gray MTR" and unable to be driven outside of tutorial, or if you are able to get the game to glitch where you're able to drive.

- TOUCHY HANDLING. If you play with an XBox 360 controller as I do, you might be surprised in that the deadzone is virtually nonexistant. You have to gently nudge the joystick in order to take a turn, and speed-sensitive steering only goes up to a certain amount. Not a major con, and some people certainly may prefer this driving style over the traditional "smash joystick against detent" style on consoles, but it certainly takes some getting used to.

OVERALL

This game has aged quite well over the years from what I can see. All-in-all it's a decent game, though I would NOT recommend it if you prefer more arcade-styled racing games, such as Burnout: Paradise, Forza Horizon et al. I've got to give it a solid 8 out of 10 personally.

Edited 2015-04-08 23:27Z to fix a fragmented sentence.

Edited 2015-04-08 23:30Z to re-organize a sentence in the damage section.

Edited 2015-12-31 00:59Z to redo lead sentence in the progression section. Lead sentence no longer implies I feel negatively about progression in simulator racing games.

Don't take any notice of negative comments these are from people expect 14 year old game to be push and play ...like be serious.
First thing copy GTR2 folder from Steam.
GTR2 and 3dconfig exe need compatibility mode XP or W7.
Then add these 2 mods will fix all issues and some.
https://www.racedepartment.com/downloads/gtr2-10th-anniversary-patch.21415/
https://www.racedepartment.com/downloads/gtr2-hq-mods-collection.21424/
Have a look how nice it looks and runs with cheap AMD 3200G tower
100 cars no problem and not a jag in sight.
See my thread here:
https://www.racedepartment.com/threads/budget-gmotor-2-0-tower.176751/
All I will say is GTL and GTR2 are simply must buys for any serious simmer, you must know where your roots come from. $12AU today for both.
P.S. SET Windows 7 compatibility to exes AFTER you install the 2 mods ....sorry.
You will also see this in 10th Anniversary patch read me by GTR233
Along with stern warnings what to do and what not to do lol

IMHO Simply the most complete and best-value PC sim ever made even until 2013 except MAYBE the pay to play ones.

As for nowadays rating:
Graphics (8/10) -has weather and time change which isn't anywhere else except for some older games which lacked others
Physics (8/10) -not at its best when sliding, difficult but rewarding
Gameplay (10/10) -many levels in AI performance, tons of setup adjustments which worked, custom weather and daytime
Replayability (10/10) -driving lessons, limitless quality mods outhere to download, many preset or custom championships, impressive collection of vehicles for its time
Price (10/10)

Total: 9.5/10

Personally this is my favourite racing game. Literally hundreds (if not thousands) of additional content available from the modding community. Also, the game doesm't hold your hand and force control off you (unless you want it to) meaning that unlike the Codemasters F1 games you actually drive the entire race. Pitlanes and post-race inlap.

16/10

GTR2 is one of the most well known and beloved racing sims for good reason. It is a game that got just about everything right and still holds up, 11 years since its release. It delivers on everything a fanatical GT racing fan like myself would want out of a racing game.

Sense of speed is great, car models, interiors and sounds are spot on, physics are excellent and the game has full wheel support with lots of options. It also has mod support as well.

The Steam version of this game does have some drawbacks. While I really like being able to own this game once more and being able to play it in 1900x1200 resolution with my G27, buyers should know that Ferrari and Porsche models are not accessible without mods, most likely to licensing issues at the time the game came out on Steam. Also, if you do not run Steam as an administrator and make sure to double click the game from your library and choose "Play Game", your playtime will not be recorded and you won't have access to the Steam overlay. It is a minor issue but it is quite annoying. This issue was also present in GT Legends.

Minor laws aside, this game is absolutely brilliant and I highly recommend it if you are a fan of GT and Endurance racing.

GTR 2 is still one of the best sim you can get. Full FIA GT 2003-2004 season, real time 24 hours race, drivers swap, animated pit stop,AI and Player mechanical failure,dynamic weather, good damage model, great physics, and it runs pretty well with an old laptop. The AI is not really good though, but there's a tweak for it on the internet. Also, i recommend you to read the engineers handbook made by Simbin :

https://www.racedepartment.com/downloads/gtr-engineers-handbook.18045/

Edit : There's some people complaining about the physics on the stock game, saying it was um well, 'arcadish'. If you want a hardcore physics of the early FIA GT cars then you could use NAPmod, it's the alternative physics for way more realistic experience on GTR2 cars, I'm using it and loved it immediately!

https://www.autosimsport.net/downloads.php
( just scroll down, and look for 'NAPmod 1.4 Patch' )

the AI is also a major problem of this game. Yes, the AI looks more natural and take various lines compared to other sims, but they lacked of pace and awareness. It's very annoying especially when you're doing endurance races, at the start they are competitive, but 1 hour later the AI were so slow that you could do a lap 10 seconds faster. Von Dutch created a mod that reduced this effect significantly, here it is :

https://www.racedepartment.com/downloads/von-dutch-ai-mod-and-tutorial.23792/
( Von Dutch said that a clean install of GTR2 is recommended. )

It is the most realistic racing sim I've driven bar GPL, so I recommend it heartily, BUT, and that's not a small but, with several caveats. Right off the bat, it's difficult. It's not unfairly difficult, but it's certainly frustratingly hard, so stay away from the game unless you are willing to sink in hours and hours practicing your skills and tuning your setups. Second, it's no looker. It was brilliantly good when it first came out (Hell, I remember drooling over the first GTR's graphics back when I played it) but these days, the whole game looks rather flat and boring. There are mods to fix the lighting, skybox and both car and track textures, but even after all the effort it will show its age under all the makeup. On a bright note, the game has widescreen support, although the menu UI is stretched. Third, it's not the complete deal; Porsche and Ferrari cars are not in the game due to licensing. You can circumvent this, again, through mods/cracks but really, it's kind of a letdown. Fourth, you should probably not really bother unless you have a wheel and pedals. Playing the game with the keyboard is torture, and controller support is weak. It's not XBOX controller friendly out of the box (which is fairly normal considering it was released in 2006) and setting comfortable deadzones and sensitivity for a controller can be incredibly frustrating. I was never able to achieve a perfectly comfortable XBOX controller setup, but to save you time the best I could get was: Deadzone 18, Sensitivity 0%, Speed Sensitive Steering 60%, and finally Steering Lock 8 degrees (in car setup). With these out of the way, and if you are still reading this, you are in for some incredibly tight and satisfying racing, which is a steal for the money this title costs.

Gtr2 has for a very long time been my favorite race sim .
And now it got even better with Crew Chief and VR support
http://thecrewchief.org/showthread.php?2012-GTR2-Setup-Instructions-and-Known-Issues
With more info here
https://www.racedepartment.com/threads/gtr-2-vr-support-not-asking-telling.193327/

And how to hex edit and fix clip planes here
https://www.racedepartment.com/threads/using-plugins-with-steam-gtr2.193547/

On top some rf1 plugins will work but it is not the full rf1 API so a lot of plugins will not work and some only partial
More features will/ might be added over the next months

Old but gold.