Sonic the Hedgehog sure has had some missteps in his most recent games.
There have been a few good ones, but I think that the majority were just bad.
Mario jumped into the third dimension very well, Sonic kind of stumbled a bit. Games like Sonic R, Sonic '06, and my personal hated, Sonic and the Secret Rings.
The, this gem came around and showcased that the 'Blue Dude with 'Tude' still has some life in him.