This book works on two levels. On the first level it is a satisfying conclusion to the Crossroads trilogy. All loose ends are picked up and, although some events see a little rushed at the end or happen off page, overall the pacing works well. Events also don't go quite as the seasoned reader might anticipate (although there is an increasingly ominous aura surrounding one character) which adds to the pleasure of the book. Warning - you may find it impossible to put down!
On the second level it is a thought provoking read about how to ensure a truly just society. On the surface the Hundred is an idyllic place to live, relaxed about sexuality, democratic and giving women equal rights yet, like Nazi Germany, even reasonably 'good' people have joined up with an army whose actions are 'evil'. Why did they join? How do you bring justice to this army? Is justice different from revenge? Is justice different from what seems expedient in the short term? At the end of the book the reader is, I think, left with a very different perspective than they started with.
Thoroughly enjoyable.