Yeah, Avengers was pretty sweet. I enjoyed the hell out of it myself. Whedon was probably the only man capable of making that film. SO much potential for horribleness, I was thoroughly impressed that they made a GOOD avengers movie. Has to be one of the hardest properties to adapt.
Whedon did a great job of having the assemble of star play off each other. I think that was the best part. Hulk was awesome in the avengers, but I think only because he was able to be this force of destruction that he is because the other characters were able to fill the other holes. I don't know if you could have a solo hulk movie...unless you went the direction of machete or something. Just outright crazy destruction.
The problem I've been having with a lot of the marvel movies is that they haven't kept the momentum. I thought Thor was real fun at the start and then it got to the end and it was just some lame fight between thor/loki. loki isn't a challenge in a straight up fight. Same with Iron Man 2. The bad guy builds all these robots and IronMan is just like let me shoot all these missiles.
Where is the good ole' fashion Rocky style/kung fu movie slug out battles where you think there's a chance the good guy could lose?