This source book lives up to the standards that Paizo has set. While I will probably never use some of the optional rules such as bartering and building a kingdom from scratch, it is still a great reference to have. Who knows, perhaps one of my Player Characters will someday wish to found a village.
I am, however, very excited about the character background ideas and tables, youth tables, traits and story traits. The mass combat is efficient and quick, which I really like and just may come in handy sooner or later :) All in all a very sound investment.