If you want to have fun playing, don't buy this game.
I'm no Sonic fanatic. I've played a few and what I've always enjoyed was the pure speed feeling of the game, as well as the "soap shoes" elements of the game. I got this game without prior knowledge of it a all, because it was on sale for 15 Euros and I needed something to play. Now I know why this game was on sale. The game greets you with a long nonsensical intro in which Sonic has some epic fight with Eggman (wow that's something new) and then suddenly gets converted into a "Werehog" (which is also a completely nonsensical term). You then fall to Earth, which also breaks apart into several parts. There you meet your new sidekick Chip. A few words about Chip: He is the most goddamn annoying character you will ever meet. His voice acting is so horrible I played the game with low volume, especially when you accidentally touch a "tutorial point" and you hear "HEEEYY SONIC!" "HEEEY SONIC". Chip is also suffering from *gasp* amnesia! Wow that is something I have never heard before and is a complete new and innovative way for character development. The dialogues between Sonic and Chip are so horrid, that a 6 year old would ask himself why the characters seem to talk like they're early 90's english dubbed anime characters. But enough about that.
The game starts you off with a classic Sonic 3D level. "Good" I thought, at least I can cancel the horrible cutscenes and just play this game. You know, so I can enjoy the classic fun concept that Sega developed, where you go as fast as possible through a level."
WRONG! After that first stage you realize that the "Werehog" levels are the absolute most boring thing you have ever played. There is just no point in them. "Oh look at me, I'm beating Eggman bots. Ok, next room, lemme move these boxes. Oh look, more Eggman Bots. Ok now lets jump here. Shit, I died. Ok lets beat Eggman Bots again. Uh huh. Ok. More Bots. Oh look now I get to press random buttons to defeat enemies."
What the FUCK is supposed to be fun about this. Simply: there is none. It stalls the action, it's unnecessary grinding to level up your powers and simple high frustration rate.
Also the 360 Achievements were designed clunky as FUCK being so unspecific you won't ever know if your'e close to achieving them or not.
Conclusion: Fun classic Sonic levels but are ruined by retarded Werehog fuckery. Also, no multiplayer.