Frankly, I think that they did a fantastic job on getting just about everything with the Hulk right. Part of the thrust of Peter David's time with the character was showing that the Hulk portion of Banner's mind came into being when he witnessed his father murdering his mother. The trauma that caused was shown well in the film and I really liked the discussion of how a physical scar if finite but an emotional scar is infinite, showing why the Hulk's power is supposedly infinite. His rage can just get worse and worse and worse as part of the emotional scarring. I couldn't have asked for better casting. Sam Elliott is Thunderbolt Ross. It's almost like a role that the man was born to play. I couldn't have asked for a better Betty than Jennifer Connelly. Josh Lucas worked really well as the slimy Talbot. I also think that Bana was fantastic as Bruce, although I will say that no poor actors have been cast in that role from Norton to Ruffalo.
The real sins of this movie are threefold. The first is Nick Nolte. I realize that they wanted some name recognition and throwing a big name like Nolte at the movie got some interest, but honestly that was such a bad decision. He obviously wouldn't do it unless the movie was about him so rather than just providing background on Bruce's relationship with his father Nolte became the centerpiece of the movie, forcing them to make him some weird amalgam of Bruce's dad, The Absorbing Man, and Zzzax. Frankly, I don't think that a supervillain was really needed in an origin film. Hulk vs the military would have been fine on its own but if they'd wanted a baddie the Absorbing Man or Zzzax would have been a decent first movie villain to allow them to build to something more significant later.
Another issue is that the pacing was weird. You get almost no action until about 2/3 of the way through the movie and then whole final act pretty much is a hulk-fest. Evening out the action would have helped immensely. I also think that Ang Lee's artsy experimentation with comic book panel style layouts didn't really endear him to audiences. I get what he was doing but I don't think that it added anything to the film and I think that many moviegoers without the comic background just found it cheesy or weird. I think that someone forgot that the general public probably doesn't really know that the Hulk was a comic book characters. Most people know him from the TV series starring Bill Bixby.
Anyhow, I think that the Hulk succeeds more than it fails. Its a pretty decent movie that's about who Banner and the Hulk are. Some details are changed, yes, but they are in every superhero movie. I still think its one of the more faithful adaptations of a character. It's a little on the slow side and takes a while to get to the action but once it's there its awesome. If you can just squint your eyes past Nolte and just watch this for the great acting then I think that many people can reevaluate this movie as the excellent film that it is.