Went to the 4pm matinee Friday afternoon; the theater was about 80% filled with more adults than kids. If you are a fan of the Marvel Comics universe of movies, you definitely want to see this one. The writers deftly weave references to other characters and events into the dialogue, which gives an added sense of substance to the story, and the dramatic events don't interrupt the suspension of disbelief a story of this type absolutely requires. There are a few moments that won't bear up under the strain of even a casual application of high school science class rigor, but a smooth application of handwavium in the dialogue makes it mostly go down easily enough. Stan Lee almost slipped his trademark cameo appearance past us too.
One thing I've noticed as the Avengers storyline has developed; with the exception of 7 people (I counted), the audience stayed quietly in their seats through the closing credits. I expect to see this technique of having an added segment of the movie being tacked onto the end of the credits spread to other production companies than Marvel Studios. This particular viewing audience reflex/expectation has been well and truly established now. I wonder how soon the cable film producers will adopt it for their work?
Two thumbs up and several "like" buttons for this one.