The first season was AWESOME, the second was litterally TRAUMATIC for your patience, the movie is nothing but EPIC.
I can say for sure that everyone should see this japanese animation movie and even if I suggest to watch it only after the vision of the previous two seasons I think that with a pair of important information before watching, anyone can appreciate this opera (wait, I'm saying 'appreciate' the movie, not 'understand why it is so epic').
Story: if you have already seen the tv anime you'll know for sure how many strange things may happen in everything titled "... of Haruhi Suzumiya", and this title is for sure no exception: the true meaning behind all the happenings becomes obvious only the very last second of what you'll see, but this won't make the movie boring or even worse non-sense as usually happen, in fact you'll find it very very good. [10/10]
Animation: I usually don't think the animations are what makes an anime a good title, but I appreciate when happenings, characters' feelings and anything should be expressed by the movie reaches you not only thanks to the ability of the directors but even thanks to the complex of animations. [10/10]
Sound: very very good, it matches perfectly whit the story. [10/10]
Characters: the part I like the most of this serie: the protagonist is as usual Kyon, a very intelligent boy that will lend us his eyes and thoughts to have the direct contact with the story. The other characters are the same of the tv anime: the 'SOS Brigade' whose leader is Haruhi, the most important character the serie takes his name from, along with Itsuki, Asahina and Nagato. Now, I would like to say something about Yuki Nagato: it's a character I liked since the very beginnig of the story, and I think the best of her is shown only in this movie (in short: if you liked her after this movie your love for her will be even bigger, if you didn't like her you'll have to change your opinion). [10/10]
Overall: this opera is a must for all anime lovers. [10/10]