Nat Almirall’s review:
Grueling to start and heavy, heavy, heavy on the pseudo-science mumbo-jumbo buzzwords, it nevertheless shines whenever Downey, Jr. is on screen. For the first hour and 45 minutes, the best bits are not the action, but the dialogue and quibbles between the group (the second-best fight is between Iron Man and Thor, and even then it's a lot of muscle-men throwing each other around), which, even then is sparse.
Still, Whedon, to my knowledge, is the first director of a superhero film since The Incredibles to get creative with superpower pairings. And the final battle is stellar. The opposing forces are nothing but body bags for the heroes to thrash, but what a delightful thrashing it is. There's a great, unbroken shot of the entire team beating the crap out of everything in their own unique ways, and who didn't get a goofy grin on the line, "Hulk: Smash."
One-liners, massive property damage (and how did they "tame" the Hulk anyway?), and a lot of really funny jokes, but a half-hour too long. Not the best superhero movie, but a good one nonetheless.
And I hope to go the rest of my life without hearing the word "Terrasect" ever again.