That's my secret; I'm always angry.

The movie is perfection demonstrated.

On the other hand, I would have liked it more if Mark Ruffalo (or was it Lou Ferrigno?) said... "I'm aaalllwayyysss anggrryyy... nnggraaaah" before hitting that gargantuan leviathan snake robot, but that's just my stupid personal nitpicky preference.

Also no need to nitpick the small things like:
--the absence of a backstory for hawkeye (i have no problem adding 15 minutes more to the movie to have this).
--that emotional moment when stark is taking the missile outer space, while pepper is calling, the movie could have squeezed more emotional juice out of the scene before rushing to end it for laughs.

We just need to highlight the real highs of the movie, like the brilliant management of time, exposure, and story.
--cap got to do his running and jumping over cars and commanding and giving orders
--thor hammerin
--even black widow had her day in the sun. brilliant acting on the scene where she thought hulk was about to flare out. Johannson fantabulously acting with just her eyeball to show fear... what do you call that?
--mark ruffalo as hulk deserves his own movie. i liked the cool-headed type when human, really angry and punching and breaking everything when he's hulk. Puny God!
--nick fury got to do his bureaucrat spy facet thing. samuel jackson is seriously embodying his role.
Brilliant turns, dialogues. The innovation of comics is fused in moving picture through the retorts and transition.
--humor in between seriousness. not everyone can balance this.
--pepper potts added to still have that leading lady thing in the movie.
--the ending of them parting ways seems like a gang who finished an operation. fantabulous.

Tremendous 'management' work I can imagine done by Producer Kevin Feige. He was able to execute everything from as far back as the first Iron Man movie in 2012. I can not imagine how hard the negotiation (in person, through phone, through agents) that was done to make this movie happen.

Brilliant, fulfilled the hype, masterful, true to form, honest to the material, what more can we say?

We have to watch it again in non-3D.