I actually stumbled across this game at Target (I was originally going to but LOTR: Return of the King for PC) and bought it for 10 bucks. At the time, I thought it was an awesome game. Looking back, however, the game now seems a little...whats the word? Lacking? Disappointing? Anyway, it's basically a direct port of he Gamecube version. Not nearly as good, unless you play this game with a game pad, where it becomes at least acceptable.
Also, there was an INSANE amount of glitches in this game. Run over to where the parking garage connects to the Train Station in Station Square and spindash. If you did it right, you'll got through the wall.
If you have a Gamecube, buy it for Gamecube. Even better, if you have a Dreamcast, buy the original game, Sonic Adventure, for Dreamcast.