Have to confess, I just tried this, and I like it. The style of it reminds me alot like the tony hawk games, but its a lot of fun when you get into it, doing all of the stunts, and smashing your bones.
Graphics are pretty good as well, nice 3D.
No matter what people say here, its worth giving it ago if you like Jackass, and make your own opinion of the game. I certainly will be keeping it and playing it through.