I am addicted to this awesome, awesome game. People can complain about the mission structure all they want but it is totally awesome. Each one feels different enough to be its own level, it isn't merely just the same level with a mission, it is a completely new set of jumps, rings, orbs, enemies, and often a brand new un-seen path.
I have unlocked all but two levels, and this game is a must have. Maybe I'll understand later why IGN gave it a 6.9 and Gamespot a 7.6, but in all honesty, I'd be giving this game somewhere around an 8.8 or 8.9. The game controls are just really, really fun, and really fun to upgrade and fiddle with.
Make sure you don't judge this game by the first hour. The more you unlock, the faster and tighter Sonic controls.
Great game. Best Sonic by a landslide, and taken from someone who has played most of the major wii titles as of yet....this is the best one other than Zelda.