I absolutely loved the Pathfinder Monster Codex, so when the Inner Sea version was announced, I could hardly wait to get my hands on it.
Packed into this 64-page book are 10 races, many of them specific to the world of Golarion (but probably adaptable to any setting): centaurs, cyclopes, minotaurs, ogrekin, charau-ka (small, violent baboon-like humanoids), derros, gillmen, girtablilu (half-scorpion humanoids), strix (flying humanoids) and urdefhans (horrible underground-dwelling native outsiders).
Each race has a brief overview, and some new race-specific rules such as new feats, archetypes, traps, spells, or magic items. Then there are 4 sample monsters, of varying challenge ratings, from a CR 3 ogrekin Kreegwood stalker, to a CR 15 urdefhan half-fiend scion, each with full stats and a description of the specific monster’s place in the world.
There is a good selection of classes used across the book, from sorcerers, gunslingers and rangers to hybrid classes from the Advanced Class Guide, including warpriests, slayers and swashbucklers. A few of these make use of archetypes, either existing ones or new ones from this book. There’s even a range of alignments, including a good number of neutral creatures that could come in handy for friendly NPCs rather than enemies.
Each monster is presented in a single page layout with a plain white background for easy printing. The interior art is absolutely excellent throughout (something that can’t always be said about Paizo’s non-hardcover products), though my favourite piece is probably the Orvian Necromancer.
For me, the Inner Sea Monster Codex is on par with the Monster Codex for its usefulness in providing more interesting encounters with the 10 races detailed here. The excellent visuals are a great bonus as well. An excellent resource for any game master.