LC and I went to see the new Avengers film on Saturday, and it's great. In my opinion, it's better than both Thor 2 and Captain America 2, but not quite as good as the first Avengers film. In particular, it's much darker and more serious in tone and much less amusing. That's a deliberate choice, and one it carries off well, but it does mean I find the former film more enjoyable.
One thing I did find very interesting about the film, and actually one of the film's strengths, is that despite this being a big action film there's a surprising amount of character development stuff in there. And, actually, it seemed to be those characters who don't have their own films (yet) who get the most spotlight time here - Hawkeye, Black Widow, and Bruce Banner.
Overall, I was extremely satisifed with the film. I doubt I'll go see it again in the cinema, but I will be picking up the blu-ray when it comes out. Also, now I really want to see a Hulk/Black Widow film (either one, the other, or both together, with that last being my preference). Which is somewhat surprising - I really didn't expect to want another Hulk film after the failures of the first two.