Recent reviews by M_

Main winning points for me are the special stage restart option and all the challenge modes adding replayablity, I don't even mind the musical changes in S3&K because they can be fixed with a simple mod.

The only issues I had while playing were physics related, because of them some death traps felt more deadly and unpredictable than what they were used to be, Sonic 2 and 3&K are great examples of that.

PS: Average 100% time is 10-15 hrs (having average experience beforehand)
Unsure if the first time trying out these games.

Difficulty; The biggest difficulty in this game is memorizing all the parts needed to complete a car, where they are, and which can you tune, nonetheless, if you complete all the combinations at least several times it gets way easier.
In short: Difficult to learn, easy to master.

Graphics; I can appreciate all the levels of detail in the wrecked cars: dents, rust, and whatnot, but I feel like there still should be more to it, I mean, holes in the frame and the detachable parts, broken glass/headlights and visibly dirty and damaged interior.
Moving onto the world, the detail is just fine, it's a barren wasteland but purposefully done for the story.
The only major issues I still have, are random very bright reflections on metal surfaces (which are the majority of the ones we work with!) and the game not showing nor letting us interact with all the rest of the car structures, e.g. steering and electrical system.

(Played on high settings)

Story; The game's story feels a lot like a side-quest, a long and often frustrating one at that, basically you have to do 30 car repairs, varying in difficulty, from being fairly fun and engaging to being unbearable due to unnecessary work you have to do to finish them, for example: dismantling the entire engine to replace 1 piston, and this happens at least twice mind you. And what's even worse is that the game straight up does not tell you which parts you have to replace and that is very important information, it's a thousand times more annoying considering that you need a functioning car to perform tests.
You can however use the wiki as a guide for each of them, and I would recommend doing that if you are a beginner, at least for the first couple, hell you know what? I wouldn't recommend doing the story missions at all until you familiarize yourself with all the compartments first.
And the story itself, it's only some random people coming by having different requests like a fisherman who has fished all over the car and a wannabe street race YouTube star with a car literally from a dumpster. Some of them pay a return visit sometimes, but that's all for the variety.

TL;DR: Skip until u git gud

Price; The price is a bit too high, buy on discounts!

DLC; Mentioning them now before you have any ideas, buy them only during discounts and read the description and the reviews first! Some DLCs like BMW and Electric Cars are good, very good in fact and if you like the game so much, you might want to check them out, but they are expensive, too expensive to pay the full price, each car DLC adds only a handful of new vehicles, on average 3 and a few new engines that you can only use for them.

Achievements; Ooh if you're a completionist, bad luck man, that's a long one. Half of the achievements are brain-dead easy like 'Visit the Scrapyard', but past that point, it gets only worse, several are extremely grindy and unfortunately they won't be earned throughout a normal playthrough. The worst of the bunch I'd say are 'Wrench Master' - Unscrew 10,000 bolts, 'Hard worker' - Finish 100 orders, and 'Time for holidays' - Finish the entire Story Mode.
'Wrench Master' - you gotta play the game I guess, avoid scrapyard and 1-star auction cars because they always have fewer parts and you'll get it eventually.
'Hard worker' - Always pick the exhaust system and gearbox orders and never: engine, suspension, and 'other'.
'Time for holidays' - Use the Wiki, and try to do at least 2 in one sitting. To describe it in one word would be: Annoying.
There are 2 other achievements I damn well should've put here, those being 'Trader' - Renovate and sell 50 cars, as well as 'Artist' - Paint 60 cars. Still, they include something I enjoy, Car Flipping, so if you do it now and then you'll get it... after a very, very long time though.

(sheesh...)
Personal 100%: 91 hours