[QUOTE=bluemonkey]
They can do great 3D Sonic games, Sonic Adventure is a perfect example of this.
[/QUOTE]
No it isn't. I'm sorry but I just bought the Gamecube port to play through again, and without the original awe that I had with seeing it and the speed when I played it 5 years ago it's really not that great. It isn't an awful game, but the poor camera, and overworld really bring it down. Plus, I thought Amy and Big were terrible characters. I know it's not the port either because I remember the problems in the original; they just weren't fixed for the port.
Now Sonic Adventure 2 on the other hand might be a perfect example of a great 3d Sonic game. It features the three best characters in the first game-Sonic, E102 (in the form of Tails and Robotnik), and Knuckles- without any of the overworld. It's been a while since I've played it, but I recall it being a great improvement over the original. I plan on picking it up soon.