I haven't seen The Avengers and I assume that it will have a great story. But in many ways, it's going to be an origin story more than anything else. The film has to establish the team coming together and working as one unit. Nolan's Batman origin story was already told in Batman Begins. The director then IMPROVED upon that in the masterful follow up The Dark Knight. Who knows what will await viewers of this third film?
The Dark Knight ended with a thought-provoking climax as Batman made a decision that few others would be willing to make: Instead of revealing the true motivations of the late Harvey Dent, the Caped Crusader opted to paint himself as the villain so that the citizens of Gotham would still idolize their hero (Dent) and not have the unfortunate reality undermine their idealism.