(I'll be intentionally vague on specific items, feats, and spells until the release date)
With Dirty Tactics Toolbox, Paizo has redeemed a number of design choices that arbitrarily limit those who favor stealthy, indirect, or clever approaches over more traditional "hit it with a big sword/spell" tactics. Dirty Tactics has options for virtually everyone, and a lot of the feats, spells, and abilities are less about power creep and more about bringing the less viable options into parity with the default "tetori monk, ragelancepouncebarian, archery ranger" tropes.
Not surprisingly, The book spends significant page count on the Dirty Trick combat maneuver, providing options to make it significantly more viable and interesting. There's even a feat for Swashbucklers (and Amateur Swashbucklers) that makes Dirty Trick pretty good starting from level 1.
Additional attention and love is given to poisoners - casters and mundanes alike - and all are given options to make poisioning... well, less bad. I still think Paizo's unreasonably concerned about making poisoning a valid tactic, but at least now there are a number of options that make poisoning an acceptable, if not optimized choice.
Stealth options are also present in the book, with feats that give rogues a reason to want to crit on their sneak attacks as well as making sniping a more viable strategy.
There are several creative and interesting spells as well. Nothing's too spectacular or "OMG Overpowered", but a number of options continue the book's general theme of making some less-viable character concepts more viable.
As a penultimate note, one particular feat solves a whole host of commonly brought up issues with combat maneuvers. Without getting too detailed, it satisfies many of the more silly prerequisites for combat maneuver feats, as well as lessens the penalty for being untrained in a given combat maneuver. Love the feat, hoping this gets made PFS legal.
Finally, I'd like to call out the Equipment Trick section for providing some genuinely useful equipment tricks - looking at you, Cape and Thieves' Tools. The existing equipment tricks were nothing to write home about, but these you could easily incorporate into any character that would fit the theme.
I heartily recommend this book to anyone who loves making stealth checks, ambushes, combat maneuvers, or who enjoys casting subtle spells. Get this book and help win the table focus back from the boring two-handed strength based types!
