here, here, and here.
The book starts off normally enough, at least as normal as any of these books in a world with Haruhi can begin, anyway. As I mentioned, we've jumped forward to December, (The series tends to jump around a little bit within its chronology) and Ordinary High School Student Kyon is ready for the year to end. Haruhi, being Haruhi, has decided the SOS Brigade should do something together for Christmas this year. As argument against Haruhi is a largely futile endeavor, this decision is finalized and Kyon heads home on December 17th. When he awakes on December 18th, however, he notices things have changed. There are subtle changes at first, like when he notices a friend is ill with the flu that he certainly didn't have yesterday, but it quickly becomes far more obvious that something's wrong. People who shouldn't be there are, and people who should be aren't. In fact, an entire classroom has vanished overnight. Most distressingly for Kyon, Haruhi and Koizumi appear to have disappeared, and Mikuru and Yuki don't recognize him at all. Only a scarce handful of clues let Kyon know he isn't totally insane and set him on a race against the clock to figure out what the heck happened.
I will say I at least initially enjoyed this book because it was material that hadn't been adapted to the tv series. Well, I've been told that it actually was adapted to a feature-length film at one point, but as DVDs of it are selling on Amazon for a shade under $200 the last time I checked, I haven't actually been able to watch this. As I sort of mentioned in my other reviews, I didn't always enjoy the other books because I was already familiar with the stories and it sort of felt like a repeat. So getting to see some new material with familiar characters was a special treat for me and I look forward to more material that hasn't been adapted.
That being said, I did end up a little disappointed with this book as well. Without going into spoiler territory it very, very briefly touches on subjects that I'm rather fond of and I felt like it truly deserved a lot more development than what it got in this novel. To be fair, the books are light novels and certainly aren't like some of the doorstoppers I've been known to read from time to time with their richly complex plots and characters. Or at least lots of explosions. But I still felt like there were things that could have been developed more in this book and given more space than what they ultimately got. I will say with the new material I kind of wish these books were a bit heftier, but I guess I can't have everything.
Ultimately, the book's okay. There's less of the awkward stuff you kind of see in the earlier books and personally I liked getting to new material, but I found myself wishing for more beyond what I ended up getting. But for the rest of you, Happy Hogswatch, Joyous Solstice, and watch out for Krampus or Krinsblag, they're some nasty fellows.