I am one of the many few who find this game awesome.
The Sonic stages are fast platforming and it never gets old. You want to play them over and over again. The controls are great and levels are well designed.
The Silver The Hedgehog stages are my favorite part of the game. it is not very fast but it has lots of fun psychokinesis parts that are just plane fun. You can pick up almost anything and hurl at the enemy.
The Shadow The Hedgehog stages are pretty much the same as Sonic stages but a bit harder. you don't go as fast but you can get cars, motorcycles, gliders and hovercrafts that all have gun fire.
Over all this game deserves a 10/10.