There are already a couple threads with specific topics regarding SFIV, but this one is a general thread about the game.

I like it! It feels a lot like Super Turbo with a bit of 3S thrown in. (I'm mostly playing Chun Li) I've finished it a few times but still don't quite have it down yet. To me, timing your moves is harder than the 2D games, the 3D animation throws me off. So it'll be a while before I get a feel for it, I'm gonna stick to fighting the computer until I'm comfortable enough with it to go online.

I think SFIV is definitely worth the hype. Though I do have my complaints here and there, I think Capcom really delivered on this one.