This message has been deleted.

There's no doubt he's selfish, self-serving and unconcerned with the fate of the young woman whose body he now occupies. I can't say he's really evil because he did not create the situation he's in or control it. He simply selfishly exploits it - he's just gotten a reprieve from a death sentence and all he cares about is that he's now free, doesn't care how or who it hurts (pretty consistent with human nature, no?).
I think Ryan tries to convey some of this in her performance; there are several scenes where she is cold, really a bit unlikeable, when she's him. When Baldwin tells her he's on to him (Baldwin's acting was excellent in that scene, btw), she stands there with a hard, cold look on her face. And on the island, when she says "you wanna give em your money, go ahead" and "Back off, pal!" you see he's kind of a tough character, with little feeling for Baldwin.
But I think the movie means to suggest, though it is not well developed, that he begins to have a change of heart. We see him very pensive at the parent's house, and when Baldwin tricks him into a confrontation he says he wanted to come. He's begun to think more deeply about what he's done.
It's unfortunate this movie doesn't explore some of these contradictions more thoroughly, it would have been a better film.