What's really disappointing about the game is how badly this port was made, especially graphics. I'm not the person that give much importance to the graphics, but in this title it is AWFUL. The framerate is hilarious, as it floats continuosly between 20-60 fps, and the model themselves are really bad, as you can clearily see the polygons... A GameCube can do better, and I believe than "DX" stands for "De Luxe"... It really doesn't seem so.
And it's a pity, because the levels structure is pretty good and solid... Levels are very well thought and designed, but this framerate ruins everything.
Anyway, the only real quest is with Sonic, as the quests using the other characters aren't very long or much inspired... Sonic levels are really awesome, though!
Another disappointing thing are sounds and music. Themes aren't much good except a few, and they result in annoying the player rather than giving the right rythm to the action. Effects good be made much better, and the dub is made pretty badly, completely out of time...
You could pass over sounds, but not over the graphics. The rest is ok, controls are easy and immediate, and they respond well (maybe the C-Stick camera could be made better as it doesn't help very much as it is)... There are the extra Game Gear games, a nice thing, but even those slow down... Incredible.
A thrown chance of restoring a very good game. Don't buy it, you'll be disappointed.