I went because my girlfriend wanted to go. Now I'm very glad I did.
The animation was very good, as were the 3D effects, and the characters were enjoyable and easily identified with. The story was good, and the pace of the movie was just about perfect.
If you want a movie that's just good old-fashioned entertaining, this movie is an excellent bet.
This one is much better than the "normal" comic superhero movie. The humor makes it lighter, somehow. Excellent casting resulted in very believable characters, whose flaws and humanity complemented, rather than detracted, from the movie. Robert Downey, Jr. and Gwyneth Paltrow were outstanding in their roles, and totally believable. Jeff Bridges was a surprisingly good "bad guy." And the lead in to S.H.I.E.L.D. left me ready for more. Great job!