Nothing special
Learning how to control sonic, is time consuming. He goes to fast, and even if you use the slide dash control he still goes everywhere, unless you keep practicing. The best part about games is learning the controls in an instant and from there you know how to play. That is not how Sonic unleashed came acrossed in my opinion.
If you think this is a adventure game, think again. Its more like a racing game then anything. It's just not Sonic the hedgehog. Developers love to take thier old games even further and turn them into a generic 3d atmosphere with a bad storyline and false advertisment for labeling this an adventure game.
Dont buy it. Rent it.