You know, one thing I really like about this is the way Hawkeye is drawn - the first drawing I've seen where his arm is CORRECTLY FORESHORTENED, and not out to his side. This ones arm appears to be extended behind his head, in proper perspective.
Interesting posing; it's cool, but it's like they're up against an invisible army. Coloring is awesome as usual, may I ask about Hulk's color palette? His skin doesn't look as "shiny" in your other drawings. Other than that, pretty neat collaboration.