I've been reading this one for a while, as it is a big, dense book, and its organization makes it well suited to reading a lengthy chapter and then putting it aside for a few days to ponder. As with his previous work in a similar vein, Guns, Germs, and Steel: The Fates of Human Societies, Collapse is above all meticulous and methodical. Augustinian is the word that comes to mind.
Probably not the best book for every reader, but I find Diamond's approach to be very persuasive, and his look at past and present societies very compelling. Recommended for those interested in history, the environment, politics, or international relations.
Collapse: How Societies Choose to Fail or Succeed: Revised Edition by Jared Diamond.