Just got back from seeing the midnight showing of the Avenger's movie, it's a comic book collectors wet dream.
I'm sure I'm going to see it at least twice more.
Down side is you have to sit thru 18 minutes of that pre-movie stuff.
So feel free to be very late to the showing.
Also after the movie ends, there are two extra scenes, one after the main credits, and one at the end of the full credits.