Been playing the 3DS version.
All three classic Sonic versions of Classic levels are rip-offs, the Dreamcast levels are shit, and the Modern levels... are kind of fun, actually.
Modern Sonic levels are all pretty samey... but eh, I felt this way with the Rush games as well.
The bosses (not the rival battles, which are boring) are actually really fun. Biohazzard might just be my favourite boss battle in all versions of Sonic Generations, no joke. I especially love his remix too. Also, Time Eater is indeed a better battle.
Nice to see cutscenes don't use 2D renders, but they're pretty confusing to follow, especially if you haven't played the HD version. I love seeing classic Sonic with his mouth wide open looking amazed; its cute!
What music was remixed is very good, IMO. Although, Modern Sonic's Casino Night doesn't fit... you can tell it was made for the pinball game.
All in all, an alright game, I suppose. On-par with Rush, a little below Rush Adventure. To be honest, even though this was a rushed effort (pardon the pun), it wasn't half bad. And the missions would add a lot more hours to this short game, I think. Not quite worth the $40 but if you liked Rush, get it if you find it for cheap.
Also, Classic Sonic does indeed feel good, physics wise. Throw away Homing Attack but keep the physics for S4 Episode 2, Dimps!
This post has been edited by Vinchenz: 25 November 2011 - 11:58 PM