Frickin' Awesome. This is one of the best Action movies I've seen in a long time, throw in the Super-Hero aspect w/ the majority of the characters being the originals from their movies and it made it even better.
Character interaction/development (especially the Hulk), special effects, fight scenes, story line/continuity, humor ('Puny God') all top notch. Now I'm going to have to rent 'Thor' since I haven't seen it yet.
Definitely recommend a theater visit for this one.