Just got back from watching it and it was definitely an awesome movie. As someone who grew up reading about these characters in comic books, this is exactly the kind of superhero movie I've always wanted to see made. Lots of action, lots of humor, not overly burdened with character development = perfect superhero film.
It also really helped that all of the set up for main characters had already been taken care of in their respective films, so no time needed to be wasted introducing them to the audience. Besides nobody's going to go into The Avengers not knowing who Hulk, Iron Man, Thor and Captain America are and I'm glad the director realized that and didn't feel the need to reintroduce them all to the audience.
Hulk did not disappoint (except I was kind of hoping that he would speak). I actually really liked Hawkeye as well and I'm not a fan of Hawkeye's character in the comic books at all.
Can't wait for Avengers 2! (Don't forget to stay through the end credits to get a hint at what that might be about.)