Sonic fans say this is the best Sonic game in years. I'd agree if Sonic Generations doesn't feel as rough and unpolished as it is.
Sonic Generations is meant to commemorate Sonic's 20th anniversary so it's got a ton of references to most retail releases including obscure stuff like Knuckles Chaotix; Also has a ton of music and artwork from previous Sonics.
Game is short and padded with a lot of annoying and repetitive challenges; controls are flaky; 2d Sonic has turning issues; On a 2d plane; Yes; It takes him a few tenths of a second to turn around.