I felt Norton on paper was a good idea, after all he did so well in fight club. However when he played Banner, he seemed like he didnt wanna be there like he was just going through the motions. It was a good movie, but not great. The director Louis was a bad pick, and it suffered from other casting and writing flaws IMO.
The Avengers however Spot On! Ruffalo is perfect, because he captured that warm quality we loved from Bixby. However he also injected his own to it, Ruffalo was INSPIRED casting. The man even looks like the hulk, which worked when he was hulk. Also the way he used some Gorilla Movements, made alot of sense with hulk. The one thing i would have liked to see translated over from TIH, is the green eyes and the green veins. Otherwise The Avengers Hulk transformation was perfect, painful and a slight of horror to it. I love how everyone was on edge around Banner, and when widow was trapt next to him she was so scared he was gonna change.