Hulk went wrong, I think, because the director wasn't content to make a comic book movie out of a comic book, and tried to mix all kinds of pop psychology into it. I think he caught the Mr. Hyde angle perfectly well--I mean, it's pretty obvious--but his story was trying for some kind of Oedipal angle that was just dull.
That was my feeling too ... I looked forward to seeing it and was bored by the over-plotting and psycho-babble.