This book introduces a few new class options, which are relatively interesting. However, they are not by any means revolutionary, and I don't imagine anyone rushing to purchase this book.
For the upcoming season 8 this book might be worth a skim but otherwise, it is a lower tier book IMO.
So that was the Society player thoughts. Now for home players, oh boy is this book cool. The new monsters added are all unique and interesting, a very interesting added template, but the best is the locations added. This book is a GM's dream for the elemental planes. If you have a campaign with any desire to travel across the planes, then this is your book.
(The classes added are really only good in a planar campaign, and don't translate particularly well ins PFS)