This book is great for those that like the deities in the setting. The rules for the included gods are thorough and cover everything you need to play clerics for each god. Granted, they don't cover everyone, like the Goblin Hero Gods or the Orcish Gods, but they cover a lot of ground for the size of the book.
So, I've been looking forward to this book for a bit. I've been wanting expanded weather and environment rules for a bit, and not to mention some more love for the nature based classes. This book certainly did not disappoint.
The class and race options are all very flavorful and interesting, with the Vine Leshy being one of the best race additions in ages. I am absolutely in love with the Terrakineticist and Geomancer (Occultist) archetypes as well, being classes that change abilities based on their environment.
As for the Spells, feats, and other player stuff, that will take some time to sink my teeth into, but I'm enjoying what I'm seeing.
Now to my favorite bits. The GM facing rules are fantastic and just what I need to run games out in the wilderness. The Discovery and exploration rules are a great codification of "hunting for hidden temples and the like" mechanics, and I will be using them in upcoming games, certainly. Rules for foraging, trophy collection, and others also really flesh out wilderness games, as well.
Now, I may be the odd man out, but these Weather rules are my favorite part. Codified, d% generation of weather based on several factors. This is important for me, as it is a great way to spice things up, as well as something that I have a hard time deciding on. The rules are quite extensive.
All in all, I love this book and recommend it wholeheartedly.