A fun, if not a little short, supplement that adds quite a bit of stuff for Pathfinder Samurai.
The town of Kawashi (the samurai town given for the setting) has some really fun and easy adventure hooks to bring players in.
The new feats are nothing that appears to be game breaking (which is always good), but also nothing new (which is okay, given the balance some 3rd party supplements lack).
I have three issues with the game, that make me rate it lower.
My first issue is a mechanical problem with the game, and the main reason I gave it 4 stars instead of 5. Simply, too many of the introduced archetypes are based on the samurai class. I'd have liked to see them take and retool more classes to make more of the base classes open to players. Not everyone wants to play a modified samurai archetype, and while you could create rules for them, to me that argument is outside the scope of a supplement review.
Gunslinger, ranger, paladin and wizard are all given nods, but in unexpected and varied ways. IE Gunslingers being used for a musket man, rangers used for a bodyguard, etc.
The second problem I have, is that the game never mentions anything about females being excluded from being samurai (which is fine, some gender roles don't need to be enforced) but the entire town of Kawashi doesn't have a single major female NPC. They are mentioned offhandedly as wives and daughters, but all of the major ones are males. (No archetypes for Onna-bugeisha either, sadly)
The same can be said about races. Everyone is a human, despite the book never calling out Kawashi as being a human-only town, but no one outside of humans are mentioned.
I'd just have liked to see the supplement address these at some point, to give a little justification.
Again, it's easily within a DM's ability to modify this, but I still feel it's outside of the scope of a supplement review.
Lastly, if you wanted a full world for a samurai game, this supplement falls a little short. The world of Kaidan is fairly unexplained here, in that everything the book gives you information on can be largely found via Wikipedia or books on Japanese culture. Short of one or two archetype explanations, you won't find anything on the world that makes it jump out as being truly unique. If you are not very good at world building (like myself), it doesn't really give you any more information to go with.
(Edit, I LOOKED BEFORE I LEAPED FOR ONCE! Make sure to download their free setting overview from http://www.drivethrurpg.com/product/85269/Kaid-
an-The-Preview-PFRPG to get a little more about the world)
Past that, the setting really has some fun stuff in it and works very well with PF's Eastern supplements. If you need a good jumping off point to start a samurai campaign, this book is worth picking up.
It's got some solid adventure hooks in the town of Kawashi that can be fairly easily expanded into a larger meta plot for the world.
Just be prepared to modify a few things!
Thanks to the folks at Rite Publishing for giving me yet another Asian themed setting to dig my teeth into! Happy gaming everyone!
[4 of 5 Stars!]