The movie is good, not great, but good.
As funny as the writing was, the entire movie really depended upon George Clooney's acting. If he hadn't delivered his part just right like he did (down to earth but with some degree of ridiculousness) the whole thing would have fallen apart. It would have been way to silly for anyone to really care about the characters.
I very much dig the way in which the "psychic" powers were portrayed, whereas the audience is never really sure whether or not they exist within the story's context. Honestly whether or not they did exist within the narrative world is irrelevant, and I think that's the point the movie tries to make.