I don't really know what to say about this book that hasn't already been said a million times. I read it in a matter of hours, I couldn't put it down.
It's "just" a story of survival and necessity, the horrible chance and pointlessness of the trench warfare and how the common soldier deals with it.
It's definitely going on my "favourite books" shelf, and I plan on rereading it soon.
Update September 2012: Last night I finished reading this book to Peter. I had long told him it was one of my favorite books, and he requested that we read it after we finished the last book I read him. I asked him if, considering how much I'd talked it up, it had met his expectations, and he said that it exceeded his expectations. While I was reading to him I noticed that he laughed heartily and looked really disturbed (depending the passage), it seemed to have a pretty big effect on him. I asked him what he liked about it particularly, and he said "The writing style." When I commented that the writing had no frills, he said, "Exactly--no
wasted words. He's not trying to write a novel, he's just trying to survive. And leave an accurate record." We talked a while about the ending, which confused him at first (as it had with me when I'd read it--"HE fell?! Who's HE??"); but he thought the whole thing fit really well together.
I have to wholeheartedly agree with the review from Le Monde in the front of the book that says it should be distributed by the millions and read in every school. From the first time I heard about WWI, I've felt an oddly personal interest in it (Peter suggested that maybe I died on the front lines in a past life, or maybe had had; I said that he was the Paul Baumer to my Kat ;])