He's a little prickly of a personality. His swagger could make him great, but if it doesn't, it would make him terrible and unbearable as a person. If his current skill set remains largely the same (needs to handle the ball, not a good shooter on or off the ball, doesn't defend), that means unless he's really good, he's really bad.
That said, if he expands his game significantly, most of that changes. What isn't likely to change is how he handles himself and that if he keeps that, frankly, cocky attitude and isn't good then it could be a nightmare.
Cocky attitude? In all the interviews I have heard he seems pretty down to earth. He does have that "Too cool for school" relaxed personality, but he seems pretty humble to me.