So while I have not read every campaign setting book, I have read many of them, and I must say that this is by far the most well written one I have ever had the pleasure of perusing. Even setting aside the subject, the flow and tone of the book was just generally pleasing to read and showed obvious skill and passion.
The subject material itself is also fantastic. The completeness, detail, and interconnectedness of the history, economy, and socio-ethnicity of the region was riveting, and they managed to cover both the big picture story as well as giving interesting personal detail about important figures.
The big reveal about the legitimacy of the prophecies was fantastic, both in its inception and in the ease with which one can build off of it.
In general the verisimilitude of just about everything in this book was on point.
There is nothing bad about this book, but there are a few things I would have wanted more of.
Oddly enough, the first thing is lack of crunch. I realize that this might seem odd considering it's a campaign setting book, but even for that it has very little in the way of player or gm options. I would have expected more than just a pair of feats for Blackjacket characters considering how hyped the Mercenary League is. That being said, I have no problems with the options that are there.
I would also have liked more detail on Kelldor specifically. While I realize that he is largely supposed to be a somewhat mysterious character, there is precious little new information about him. I would have loved have gotten a stat block, but really any description other than rich, wise, and charismatic would have been nice.
All in all this has been my favorite Pathfinder book I've read from any line, and I cannot wait to read the next book that these particular authors team up on.
