If you're like me and you adore the Lore of the Pathfinder universe, this book definitely pulls you in and provides details into several small plots that any GM with a mind for it can work into their campaign.
Such delicious tidbits include:
The Cult of Alichino in Ustalav
The Test to become a Hellknight
What happened to the Book of the Damned after it escaped from Heaven?
A Gallery of Damned souls who are all connected to various events in Golarion History, rightfully receiving the punishment they deserve, but all of which hold secrets to vast treasures any Adventuring Party would die for!
All in all, I'm quite pleased with this book, and recommend it.