It's weird how (the fixed) Iron Man is not looking at the direction where he's pointing his palm, and that the placement of Thor's helmet looks as if it's floating. Captain America now looks like a lady, maybe because of the head-body proportion. Hawkeye's shades, in my opinion, is not really necessary as well. But overall, good job for the effort you made!
i have to say i do like how marvel just threw this together. the layout sucks. this is not a reflection on ur work at all but marvels. come on ur a billion dollar COMIC company lets get some balance and composition. still can't wait to see the movie though... oh and Cap should be up front. he is the embodiment of the avengers, we all know this!