At the time of this writing (and technically after having seen the film subject to this review), I have watched just about all the anime related to "Haruhi Suzumiya." I don't particularly watch a lot of anime descrbied as "quirky-romantic-comedy-set-in-high-school," as there are simply too many such anime to count, and most of them not particularly worthwhile. So why did I take up the show? What it for the hype and fame? No, I watched it so that I could watch the followup film "The Disappearance of Haruhi Suzumiya." In the early 2010's, "The Disappearance" was cited by many fans as one of the best anime films of all time. A big comment from something so closely tied to a existing franchise. I heard the visuals, the animation, and the direction was on a whole other level from most anime, and the story was so emotionally powerful that it justified everything fans put into the main series. At 162 minutes, it is also cited as the longest animated film (in the world) ever made, only second to the more-difficult-to-obtain film "Final Yamato" at 163 minutes (and as that that's a special director's cut at one 1 minute longer, I consider "The Disappearance" to be the real holder of the claim). At the time, I was just starting to seriously get into anime, and I wanted to see the best it could offer. So I watched the first season of "Haruhi Suzumiya" and proceeded to watch "The Disappearance."If you too walk in purely because of the hype, you will be disappointed. Very disappointed. "The Disappearance" is very much a movie for die-hard fans of the original series. If you haven't seen or outright hated the original television series, this will not be worth your time. However, if you have seen and had any enjoyment from that main series, then this film is required viewing, and there is a higher level of competance in the craft on display than what Kyoto Animation had made prior, signaling what fans of the studio could expect from their now well-respected production quality.The story starts around Christmastime, and as usual Kyon hangs out with Haruhi and company at the SOS Brigade, a school club that searches for paranormal activity, while its members secrety keep Haruhi occupied from unknowingly activating her God-powers and rewriting time and space. Despite my description, this is becomes commonplace for Kyon, and despite his complaints, he seems to have grown accustomed to the lifestyle. However, one day Kyon wakes up, goes to school, and finds that Haruhi isn't there. And no one recognizes her name. And the SOS Brigade doesn't exist. Even his closest friends don't act like themselves, and don't understand what Kyon is talking about. Haruhi was forcably the center of Kyon's world for so long, and now his life has become... well, normal. Without Haruhi and the existance of espers, aliens or time-travelers, he can finally get back to a life of a normal high-school student. But is that what he really wants?While a good setup for drama, this plot plays out more predictably than you might think. Which is not to say the mystery and drama involved isn't engaging. While Kyon's reaction to the new world is frustrating (he seems to spend at least 30 minutes freaking out his school before understanding that Haruhi is really gone), his emotions come out in full force in this film then they ever have before. Nagoto, known to be a quiet and emotionless figure, now is a timid and shy girl, and she gets more attention in this film then ever before, enough so to make fans completely fall in love with her, despite usually being strictly a side-character. Of course, the mystery of what exactly happened to Haruhi, and why, is fascinating: did she herself cause this? If so, why? If not, who did? 
Generally, the story succeeds at being a strong arc in the Haruhi storyline, but is a little longer than it ought to be. Its over 2 1/2 hours long, and I strongly feel they could have cut this time in half without losing anything important. And the most important factor is that you MUST have seen the original series. The film will make references to both Season 1 and 2 of the show, some in passing comments, some in scenes where remembering what happened in those scenes is crucial. The first time I saw the movie, I had only seen Season 1, and was annoyed at how often the dialogue referenced certain scenes (many refereneces of which were purely for fanservice, saying "hey-remember-that-part-of-that-show-you-love?"), and how important scenes to remember weren't well-explained to understand the context. So given that you MUST invest your time to watch 28 episodes of the original show, and then must sit down to watch 162 minutes of movie, I suspect some viewers will be left with a bad taste in their mouth. If you don't feel any minute of the series was a waste and are eager for more, then you are exactly the audience this movie wants, and you will be rewarded accordingly.Kyoto Animation did a good job bringing Haruhi to the big screen. The character designs are the same, but rendered with slightly better fidelity and detail. The animation is also a slight improvement, best seen in the subtle moments, be it in characters walking home or tears swelling in a character's eyes, sometimes in slow-motion for effect and to show off the attention the animators put in. Setting the story at winter was also a smart choice: the whole movie recreates the romantic longing of falling snow outside an empty school, seeing your breath in the quiet air. The backgrounds at times look so detailed you would swear it was real. The direction takes its time, and despite the dialogue lengthing scenes more than it should, secnes with no dialogue are beautiful in layout and in time. The music is soft and slow, leaving a greater impression than the upbeat music from the show, better in tune to the atmoshpere. The English dubs finally give the actors a chance to show off their acting chops better than they could in the show (again, too much dialogue though...).Upon further thought, the film mkes a clever metaphor of how life innevitably changes. The school life everyone grows accustomed to must also one day change, and so you should savor each day while you can. This isn't a subtle theme (the film basically tells you this halfway into the story), but its a relatable one. And love it or hate it, some of the scenes would excite fans better than any fan-fiction, and for a sequel to a franchise, you can't ask for more than that. But all of this heavily depends on you and your opinions on said franchise. I have now seen and did not particularly enjoy the whole of the "Haruhi" anime, and I can confidently say that "The Disappearance" is NOT the best anime film ever made. There are dozens that came before, and dozens that came after, that are significantly better in every aspect, both as art and as entertainment. Perhaps the hype was partially because films tied with existing anime (ie: sequels, prequels or retellings) have a bad reputation, and even then I can point out several that exceed this. But ignoring the hype, "The Disappearance" is still quite good, and on a winter night while you recall your early days with a student-anime club watching the original series, this can trigger something in your soul that reminds you why you watch anime at all.