He wasnt unhappy with the final cut, he was unhappy with the running time. Its already been said that it was blown out of proportion, he has no problem with the film. But because of the American History X thing, a big deal gets made. Anyways, Im really looking forward to this movie...
I read, i belive on ign.com, that Norton was unhappy the cut he helped make was not selected as the final cut. The studio went with Leterrier's approved cut because they said Norton's cut was too bloated and the pace was off. IGN also reported that Norton worked very closely with Leterrier throughout the project and was very keen on doing things a certain way. Apparently he is a huge Hulk fan and wanted certain things done and written in a specific way. But he is known to get heavily involved in all his projects. Though he now says he's happy with the film, ultimatley his cut was not chosen so I am sure part of him is unsatisfied. As anybody would be.
I just hope the flick is bad-ass.