I just had to replay this game again, it's great and one of the best 3D Sonic games.
Things I didn't like, the game has too many pointless levels, yes, ones that can be finished in 30 something seconds, I don't know what the deal is there, just make them a part of the other levels and thus have fewer but longer levels. I hated that when you lose a life, the timer does not reset to last checkpoint, instead it just keeps going, there's also no more 100 rings and get an extra life, which I could've used a couple of times, there are some of the usual cheap deaths here, only way to get those extra lives are to find them in certain levels or get an A rank or higher at the end of a level. As for the bosses, I didn't like them at all, except for the last one which probably, not sure, but it may have the best music in any Sonic game. You'll finish it in just over 3 hours, if you're going for all the red stars and S ranks, be prepared to spend a lot more time, naturally. I also think some of the dialogue is fairly lame, however I do like them going back to being more fun and lighthearted. I liked the doom and gloom stuff, with an apocalypse and characters dying and everything, but it could get very heavy handed and overblown to the point of being ridiculous, I appreciate this direction as well. Okay, so like ANY other 3D Sonic game, it isn't perfect, but it's a really great game nonetheless, and you should definitely check it out and Sonic Generations as well, the blue blur has never been better in 3D, and I can't wait to check out Sonic: Lost World for the Wii U, hoping it's as good as Generations or Colours. Recommended to Sonic fans.