As someone very invested in PFS Organized Play, this is one of my favourite Player Companions to date.
I appreciate the focus on the Pathfinder Society as an organization first, when compared with something like the Pathfinder Society Field Guide. I also very much like the focus on how Pathfinders are similar and different from other adventurers. To that end, the sections that cover character building and joining the society are great, and should frankly be required reading for someone who has played more than a few sessions of PFS (Read: I'm tired of seeing the 7 Int/7 Wis/7 Cha characters who somehow made the cut and became Pathfinders).
As for mechanical options:
Featwise, there are some poorer choices than others, but that's not new for Paizo. Improved Day Job and Steadfast Mind seem to be entirely for padding word count, and it's those feats that are making me wish for a 4.5 star rating. Oh well, other options make up for it. Planned Spontaneity and Emergency Attunement are both fantastic feats (the former possibly a bit too powerful for the already strong prepared spellcasters), and I really like Cut Your Losses. The traits added are nice, although I worry that with Canny Wordplay, Charisma is becoming more of a dump stat than it ever has been. However, Ultimate Campaign already crossed that barrier. Insistent Benefactor and Muscle of the Society are both winners.
The prestige class is weaker than going single classed, but that's how all prestige classes are in Pathfinder. As is, the Pathfinder Field Agent has some cool abilities, and a character that takes that class will be able to emulate the Society's focus. Weaker than some, but still good enough, and certainly cool enough.
I'm happy to see new ioun stones and resonances, but I'm happier still to see new PFS vanities. Please keep adding these Paizo! The other magic items and spells available are all conducive to the Society's motto, and I have no complaints about them.
Other reviewers have complained about this, but sections like 'Five Spells Every Pathfinder Should Know' need to keep happening. Not only is this good advice for players, but it makes so much sense that operatives trained by an organization would go into things with a similar idea of how to be prepared.
Art is good, but Amiri looks a little dopey in her picture. Maybe she's about to sneeze?
All in all, this book is exactly what I want in a Companion. You educate me on the organization, give me some insights into its philosophy, and give some new and different options and items, all without too much power creep. Bravo.
This addition to the Pathfinder ruleset provides a great degree of help for many of the weaker classes, which is amazing. The help for the Monk alone has me torn between three different character concepts, so that in itself is excellent. My personal favourite part of this book, however, is how it's just a good read anyway. The pictures are interesting, and the fact that each feat (even if some are questionable and possibly not particularly useful) gives a new and flavourful way of being a hero is a very exciting thing. The style feats offer many different versions of what was before just an unarmed fighter, and the Ninja is what the rogue always should have been. If you like the Monk, the Rogue, unorthadox fighters and dishonourable paladins (the holy gun archetype, in particular), or if you like guns(!), then this book may be worth a look.
Unfortunately, I've come to expect a certain level of quality from Paizo, and that's why I can't give this product 5 stars. There are editing mistakes, and some of them make this book seem very rushed. Typos are one thing, and I'll expect one or two in a final draft, but some pages refer to feats which no longer exist or have been renamed. That part is sloppy, and I look forward to the errata.
It's still a good buy, however, and I'm happy I bought it.