Keep in mind, The Hulk was not really a "hero" in the sense of the word. He's done more damage to the Earth than protected it. Sure, he's gone up against villainous types, but in many ways, he can be considered a villain himself, which was always the inner struggle for Bruce Banner. Heck, in the comics currently, the Illuminati (Professor X, Iron Man, Dr. Strange, Black Bolt, Mr. Fantastic, and Namor) have thrown the Hulk into space, where he landed on a far off planet where they still have Gladiator matches, and he's a local hero there because he is a winner. However, it seems he's heading back to Earth this summer to take revenge on Earth's heroes of his banishment.
Eric Bana was a pretty good Bruce, but I do like Edward Norton in a lot of movies, so I think he'll be good. I'm actually a bit excited so far!