Two words: Loved it.
Two more: A lot.
I realized tonight that I don't think a Marvel Comic movie has ever let me down (I dare you to prove me wrong!). This movie is certainly no exception to that rule. If you're looking for a great action flick with heroes and villains, superhero fight scenes, a pretty solid plot, and even a bit of a sappy love story for all you ladies out there (and you, Mr. Hopeless Romantic), this is your movie!
The bottom line: I enjoyed it from start to finish. I give it an A.