Rayman Jungle Run from Ubisoft has just hit the App Store, a day early. It's no where near as complicated as its console counterparts, but then it can't be because touchscreen games are obviously a lot different then console games.
Instead of pressing a button to run and then pressing another to jump, Rayman runs automatically. You simply tap when required.
The graphics and frame rate are brilliant. It's super smooth all the way through. The backgrounds and gameplay area do change throughout the game which changes it up - so you're not stuck doing the same thing all the way through.