Wow. Just wow. My new favorite movie ever. I cannot get over how good this was. Joss Whedon is a God. Great use of all the characters, a plot that makes sense, non-stop action and meainingful plot, lots of SJ bootie shots, unreal visuals, and a handful of great jokes that had the audience rolling. This one's got it all. And the Hulk...Ruffalo really does steal the show. Avengers fan or not, this movie is a must see. I can't wait to watch it again!
Spoilers for those who missed the clips at the end:
The first clip hits about 1/3 of the way through the credits. There's a discussion between two aliens, as one is telling the others that the humans were not the weak, easily dominated species they initially thought, and that attacking them again would be "courting death." The second alien, who is obviously behind everything, turns and smiles, and is revealed to be Thanos. As Marvel guys know, Thanos does court death.
The second bonus is at the very end. After they win the day, Stark says they should take a few days off and go out for some kind of dinner...I forget what the type of food is, but he says they should try it. So, at the very end you get about 2 minutes of the team just sitting there chewing on some lunch. They do not appear to be enjoying it. There's no big reveal - just funny to see the 6 superheroes hanging out, not enjoying lunch at a restaurant.