Saw it in 3D. It was amazing!
The 3D helped with the immersion and made things feel vast. The flying moments in 3D were great! The plot was complex but easy to follow both for children and adults alike. It doesn't treat the audience like idiots. Seeing the first movie would help you understand some of the characters though not really required IMHO. Some very touching moments, and my girlfriend cried a few times. If the first movie was about a parent and teenager's relationship, this one is about becoming an adult. The music fit the movie perfectly, the visuals were beautiful, and the voice acting was amazing (Cate Blanchett!). There are no post credit scenes but the beginning of the credits show concept art that was amazing.
Of the movies in theaters I've seen so far this year, I am ranking this as top. Still need to see Spiderman 2 and X-men:DoFP.
So much I'd like to say but it would be spoilers. Go see it!