Really, to call it a great comic book movie is shortchanging it. The Punisher (2004) is a great comic book movie - over the top, two-dimensional, cartoonish violence, with dialogue that consists of grunts and wisecracks. The Avengers is a great action flick, generally. This is much more of a "Team of Bad-Asses Who Don't Get Along with One Another" film and should be compared to those (and compared quite favorably, allowing for tights and people who fly and what-not).
Fights are choreographed amazingly. Such intensity, they have you grunting, clenching your fists, grimacing. They reminded me of the insane sequences with Whiplash in Iron Man 2 (though I checked to see the directors are different). And so complicated, considering the number of combatants, the fact that it has to be in three dimensions, and incorporate a combination of a plethora of weapons and explosives, but also include bone-crushing body-blows. I kept thinking to how bad the action sequences are in a Michael Bay disaster - just so much going on, I long for it to be over and I can stop being dizzy and bored. These kind of fights here, I'd watch all day, every day.
Dialogue doesn't get too far beyond grunts and quips, but to give credit - the wisecracking is well-balanced and doesn't go all the way into camp. It's just the right level to lighten the mood and make the whole thing more enjoyable. This is Iron Man's forte for the team and the writer did a great job. And really, the ponderous dialogue earlier on (it gets drowned out later by clobbering) about human freedom isn't embarrassing: I'd be very surprised if Whedon hasn't read "The Grand Inquistor" chapters from Dostoevsky, and he has no reason to apologize for his version for the masses - it gets the main points across. This is pop culture at its best.
I was surprised so many cultural references were aimed at old folks like me. I suppose they're assuming we'll bring kids (mine are too big to be seen in public with me, alas). Having Iron Man refer to Thor as "Hey - Point Break!" Really? How many people got it when he said that, or when he said Loki was working with an "Acme dynamite kit"? Brilliant for anyone my age. As was having a cameo from Harry Dean Stanton (who always cracks me up) saying, "Hey are you an alien?" Had me howling, to the confusion of the teens all around me. I doubt most other people in the audience quite understood why Iron Man was wearing a Black Sabbath t-shirt the whole time.
Now, please excuse anything too graphic in my evaluation of Ms. Johannson. I don't think she's an awful actor. She has decent inflection in her voice (which drives me crazy when people can't enunciate or vary their tone), and she uses it to express some emotion. Even sounds a little scared with Loki at one point (well filmed, with Loki's face reflected in the window). BUT - she has one facial expression: pouty, but focused (or focused but pouty, I don't know). And as beautiful as she is, in closeups, you can see how the makeup is slathered on, especially her lipstick, and it looked pretty clownish and unappealing. And finally (and here's where I ask indulgence) her body is filmed (especially from the back) so lovingly, and her part's blocked to accentuate this to almost ridiculous extremes. So I actually noticed when the Kevlar spandex didn't hug her perfectly, and all I could wonder was "Is there someone in charge of that? And how would s/he be credited at the end? Just, 'Special Assistant to Ms. Johannson'? Or maybe 'Body Image Consultant/Editor'?"
So, the short version is - go see it!!