Matt Zoller Seitz writing for rogerebert.com
It would be silly to position Marvel or Whedon or their fan army as underdogs. Once a niche genre, superhero films are now practically the official culture of the United States, and this entry will make a fortune no matter what anyone says about it. Still, I hope that even as people buy tickets out of habit, they'll see that there is, in fact, art happening on the screen, maybe for the first time since Marvel's march through American cinema started. "Age of Ultron" proves that a movie with stealth fighter jets, levitating cities and Hulk-on-robot fisticuffs can be as freewheeling as a no-budget indie. It's a shame to think that this film will be dog-piled for its imperfections rather than applauded for trying to prove that a seemingly inflexible genre can bend into strange and surprising shapes.