To sum this movie up in a few words:
2 and a half hours of AWESOME.
No seriously, it was really really good. I actually went to see it twice in the theaters, which isn't something I normally do.
I dunno, I thought all of the characters had pretty good screen time (except arguably the Hulk, but he did a lot of rememberable badass stuff to make up for it). I'm looking forward to the sequel as well, I love the Marvel movies.