This is probably one of the best Pathfinder resources for DMs. I love the 'classic' monsters, but it can be hard to use them in other than their typical niches. This book takes care of that and lets orcs, kobolds, and the rest be diverse enough to keep the players guessing.
In a lot of ways, parts of this module plays like a turn-based strategy game (Civilization, Alpha Centari, etc). I, for one, love it. I'm already finding places to employ these kingdom-building rules in other parts of my campaign.