It may seem like the following review is the same as the one I gave for Ultimate Magic. Well, it pretty much is, because I feel pretty much the same way about both.
It's hard to take reviews seriously on this board. If you're a longtime lurker or poster, you know well that every additional book Paizo has put out for Pathfinder has from its inception been a bright, shiny target seemingly custom made for the hurled monkey poo of a horde of miserable would-be design "experts." These people spend six months at a time lurking in the forums and throwing hate on every idea as it is being tested, so should we be surprised when they rain their hate down on the product once it has been released?
Here is a frank and honest review from somebody who actually does make a side living making games and related accessories, and who doesn't have an axe to grind or a big fat ego to polish.
I love this book. I admit, I don't use all of it. I don't care. What I use, I love. What my players use, they love. Nothing here has yet broken the game. Nothing here is out of whack or out of balance. I make great and memorable NPCs from this material, and I have never been so happy doing so.
This book, as with Advanced Character, and Ultimate Magic, continues what Paizo does best. They zero in on what options were missing, or were cluttered, or required five 3.5 books to accomplish, or that were originally poorly conceived by 3rd parties, and they improve on them and put them all in a nice, clear, tidy reference for me to have all the fun I wanted to have, but never did.
In short, the book provides great fun alternatives, and covers a lot of ground, making the work of a 3rd party designer like me, a whole lot of fun, and accommodating a wide variety of imaginative builds.
And a note to those who compare the information offered in these books to 3.5 variants. Yes, you've seen some of this before, and we get it. You are bored with it. But it is a gigantic ego trip to think that the only people Paizo makes these books for, is yourself. There are new players Paizo has to think about, too. Players who have not seen these ideas before. Give a matter a little thought and try not to be so eager to deal out spite and venom.