It was very good, not great.
Best non-TDK comic book movie, easily. I am glad it cements Joss Whedlon as a viable writer/director, as he's one of those rare qualities like J.J. Abrams or Chris Nolan.
One of the greatest popcorn movies, but certainly not in my top 10 by a long shot. Really worth the $5 I spent, though.
*edit*
The scary thing is, a movie this good is going to likely be drown out by the exception quality of other movies. I have been looking forward to this year at movies since I knew The Avengers and TDKR was coming out. There are about a dozen solid movies coming out this year, and TA may be the 3rd or 4th best once it comes out. Of course, I am going to watch Prometheus in IMAX or whatever format I can pay for, as I've been excited about it for two years now. I hope it re-invigorates the sorely lacking Sci-fi genre, as its been pretty much dead for a decade since The Matrix: Reloaded killed it.
Back from the dead, I'm afraid.