One sentence capsule: This product is a waste of time, energy, money, and space, that simply culls flavor text from other, better products and puts it into a single deeply disappointing volume.
Slightly expanded review: As a dedicated player of humans, I had long been disappointed by Paizo's lack of options for that race. Although we are repeatedly told that humans are Golarion's most adaptable, widespread, versatile, and successful race, there is virtually no game-mechanic crunch to support that. The extra feat and extra skill point equate to raw power, yes, but there is virtually nothing a human character can do that a member of any other race can't do as well. Dwarves get Steel Soul; elves and half-elves get the Arcane Archer prestige class; gnomes get Gnome Trickster; half-orcs can have Keen Scent; halflings are sometimes Well-Prepared. Humans can be Eclectic or have Racial Heritage, which...lets them act more like other races. This is the book that should have filled that gap, but instead we get more fluff about different cultures and a couple of pages about a god who's been dead for a century.
This was a chance for Paizo to give players reasons why humans are so successful in so many different areas of Golarion by giving them something, anything, that they can do that other races can't. A few feats, a prestige class, something. Instead, Paizo fumbled its roll.