First off let me say I was really looking forward to this book for the last several months for the 'Elemental Purist' archetype which in all honesty...really kinda sucks... it has the right flavor idea but mechanically only the change in Endcap ability is really fitting for the theme and has me really disappointed for hopes of a more Earth Dedicated Geokineticist(the template has promise though)
The rest of the book is pretty solid but seems to be even more lacking in stat details than many other books I've purchased lately. While the info on the individual planes, the local denizens, their attitude and motivation and 'interesting places' is great getting their stats can be a challenge(references to things like RotRL collector's edition, Curse of the Crimson Throne, Book 5 of Mummy's Mask, etc). Also somewhat disappointing is the total lack of stats for 3 of the Elemental Lords and little to no information on the Fallen Lords(plenty of room for homebrew campaigns I suppose). I was really looking forward to seeing the stats for Ayrzul but sadly only Ymeri is stated out. The creatures are interesting and appropriate for the book as expected, for the price the PDF is a decent enough deal for those truly interested in the planes either as a PC or DM and opens up a lot of potential.