OK, here's my review...I'm playing on an iPhone 3GS 32GB if anyone is wondering.
Good:
-Gameplay is fast and fluid.
-Graphics are excellent for the characters, especially during the Ultras.
-Control is surprisingly responsive. The touchpad controls aren't as irritating as I thought they would be...they seem to be modeled after the GBA SFII Turbo Revival.
-They've captured the "feel" of SFIV pretty well.
-Sound is PERFECT.
-Lots of gameplay modes, including training.
Bad:
-Background graphics are TERRIBLE. Completely static and blurry.
-Controls need to be tweaked...the game is unplayable without using the separate touch button for special moves. The "touchpad" SUCKS for special move input, but the special move button makes up for it a bit. It still encourages a lot of button matching, and takes a lot of the technique out of the game.
-The amount of characters (8) is very limited.
Here's the thing: If you're a serious SFIV tourney type player, don't bother with this. You'll HATE it. If you're a casual fighting game fan, it's probably the best attempt at a fighting game on the iPhone, and it does play really well, but it isn't the console game.