Read this for a Tolstoy and Dostoevsky class, and while it is very good, I think it would be even better had I not needed to read the whole thing in under a week. Though it's a short book, it is very dense, with a lot of detail and one-or-two-page long paragraphs, etc.
All in all, the very un-Dostoevsky documentary approach to prison life is amazing when it's good, but a bit uneven. He based it almost all directly on his experiences (with a few additions, mostly for the purposes of rather offense ethnic humor, for some reason) but almost always omits the narrator's own feelings. Dostoevsky the psychologist is there, but in his outside look at the other prisoners, rather than in a deeply introspective look at the protagonist. A great read, very affecting and interesting, but different from most of his work (I've heard, it's the first of his I've read for the class) and not across the board good. The potential for who he would become is absolutely there, though.