Visually, it's probably the first decent 3D that I have seen since Avatar as well.
This is the first movie that i have though was worth the 3D, i was not that impressed with the 3D in Avatar. The way Avengers is filmed in 3D is MUCH less gimmicky. I felt comfortable recommending that my cousin and her boyfriend spend the extra cash for the 3D version of this movie.
Actually, the only reason i went to see The Avengers in 3D was because i got platinum tickets from school for 7$. They were valid for 3D movies as well as 2D, so me and my buddies went to the 3D option.
p.s.
Firefly was a very good show, and serenity was a pretty killer movie as well. Ahhh nostalgia....