Okay. Here it is. No spoilers, but details are mentioned.
1) Mark Ruffalo is a revelation in this film. I thought he was sublime, twitchy and by far the most interesting character in the film. His scenes are tragicomic.
2) The jokes are perfectly timed and executed. Instances involving The Hulk are by far the highlights of the film for me. His opening scene is both tense and unpredictable.
3) Besides a lackluster opening action sequence, the film has escalatory scenes that manage to incorporate each hero adequately. Also, the final 30 minutes are pretty badass.
4) The pacing, aside from the opening 30 minutes, is well done. I didn't check my phone once the opening act was done.
5) Loki manages to be a (mostly) capable villain, though he is not particularly intimidating. His scene ordering civilians to be subservient was a nice touch.
6) Tony Stark. He steals his scenes, but Mark Ruffalo steals the show.
7) In two hours, The Avengers managed to make me care more about each character as a whole. In watching Thor, Captain America, Iron Man 2 and The Incredible Hulk, I felt cold and uninvested in the characters. Whedon manages to work each character perfectly.
Summer can now officially begin.
4 stars out of 5.