OH HELL YES I RECOMMEND THIS!
I've always been a sucker for Street Fighter games since Street Fighter 2 on super nintendo and it's my all-time absolute favourite game franchise alongside Serious Sam and Doom so keep that in mind while reading, I'll strive to be as objective as possible but it can include some bias.
I wasn't such a fan of the first SF4 which I had the occasion to play long time ago and was basically keeping going on Street Fighter 3 third strike (which is an awesome fighting game you gotta try!). But oh boy how things got better with this one!
The learning curve is top notch provided you have the patience to spend some hours on challenges and training room to find out some new tricks and combos. So far, the whole things looks extremely well-balanced and could never complain about a character being too cheap or overpowered (unlike that infamous vanilla-Seth who made me wonder if I was playing Street Fighter or some SNK stuff). The whole gameplay can look pretty SF2esque at first glance but in fact it includes many subtleties I'm discovering hour after hour with pleasure. It's one of those "easy to handle, hard to master" games and even though I'm still basically losing online , the progress I did is extremely gratifying.
Online playing so far went good, I sure can't complain about the lag when defeated wich is a good thing. They included a replay mode which can record your matches if you wish and it's extremely useful to see where you sucked (no, don't tell me "it's boring to watch" DO IT. You can't imagine all the little flaws you can realize when the pressure went down.)
Don't listen to guys on forums who speak about cheaters. I didn't spot any cheater here, just experienced players and it's pretty exciting to have such a challenging crowd!
Training mode is also one of the best if not the best I've seen so far with a ♥♥♥♥♥♥♥♥ of useful options.
For solo players, IA is ok, but don't ever think that because you just started to master hardest mode you became the Street Fighter God of Battle. Because it's not enough to stand a serious chance online believe me. It will be challenging enough for not so experienced players and allow you to train a bit against characters you don't know (DO IT.) but that's pretty much it.
One last thing : don't listen to reviews saying online gaming is broken , because this issue has been fixed!
So well, this fighting game delivers for casual players as well as for experts you can't go wrong with this one, just grab it!