Let me start by saying what this book is not: It not a history, chronology, or review of the long-term consequences of the Peloponnesian War. If you want a history of the war, I recommend Donald Kagan's excellent book "The Peloponessian War." In fact, if you are not already familiar with the war, I highly recommend that you read that book before attempting this one.
The nearest I can come to classifying it is as a military history of the war: it discusses the tactics and methods of fighting the war, how they changed over the course of the war, and how those changes revolutionized not just warfare but how the Greeks viewed war and society, with consequences for all of Western culture.
Hanson argues that at the beginning of the war, war itself was regarded as a heroic endeavor worth engaging in for its own sake. By the end of the war, writers were more likely to talk about the high cost of war and question its value. The change came about because of the increasing brutality of the war, which eventually became something much like "total war" as we would understand it - war without rules or limits, where civilians are targeted and suffer as much as (or more than) official combatants.
The book also tries to give the reader some idea of what it would have been like to live through the Peloponessian War, as a citizen of Athens or Sparta, or any one of the many other city-states in Greek that was swept into the conflict.
If you are interested in the history of warfare, rather than just learning the names and events of the Peloponessian War, than this book should both entertain and educate.
Very hard to read. Too much like a Microsoft manual. The author either assumes you are very well versed in Greek history or is trying to prove how well HE is versed in it.
He jumps all around the geograhy and timeline in every paragraph.
I found myself skimming to glean the insights and descriptive tidbits buried in his text.