Story: I've mentioned this before but anime movies usually disappoint me. They like a really long filler episode. However, that did not apply to Vanishment of Haruhi Suzimaya. Imagine a really good arc of Haruhi Suzimaya. Ok, now translate that into a movie and that is what you get. You get the intricate story line, strange comedy, and unexpected twists. It had everything I loved from Haruhi Suzimaya. However, you will need to see both seasons in order to understand the movie (I had not seen season 2 and ended up being confused for a good portion). Haruhi Suzimaya lovers rejoice because this lives up to the name.
Animation: I already liked the animation for Haruhi Suzimaya so they basically upped already great animation. The character's expressions are what stands out the most and they are phenomenal. Seriously, they are stunning.
Sound: I loved the soundtrack. I am a piano lover and pieces were lovely. I would love to get the soundtrack and the sheet music to play the pieces. I originally watched Haruhi Suzimaya in English. Big mistake. I should have just watched the original because I do love the seiyuus.
Characters: Two of the major character developments you see are Kyon and Nagato. I don't want to give anything away but they are both done excellently. Since it is a movie, you obviously can't get a large amount of character development from a wide number of characters. It's good that they stuck to two and did them both well.
Overall: If you love Haruhi Suzimaya, you'll be blown away. I would definitely watch this over again.