The movie doesn't portray him as evil at all, imo. He comes off as witty and quite good at evaluating risk.

As for his hacking abilities, I've heard stories that he's not (or is no longer) among the best; perhaps he's better at coming up with creative uses for a system than actual coding. And for what it's worth, I don't think the movie made him out to be a "genius hacker" in the coding sense -- more a genius hacker of what the Internet was intended to be.