Absolutely wonderful book.
I know this is going to seem like a cop-out; I know this is going to be generic or boring, something you shouldn't bother to listen to because it's probably just someone that doesn't know anything and they're putting in a good word because they don't know anything.
It's not. This book is one of the best things I've seen for weeks.
Every magical weapon property is - if not, as most are, completely on-par with that in the original book - very, very close to being balanced. There are very, very unique ideas brought up - Dessicated is something you'd actually feel fine using, and gives a very good feel to the weapon, while Dark gives a very proper trade-off. Adaptable gives a unique adaptability (an unintended comparison! It does what it says on the tin), while Enhancing gives atypical weapon-users the ability to step up.
As far as tradition, though, Seething Energy advances one of the most common bonuses (who hasn't heard of a +1 flaming longsword?), while Slaying gives Bane a very lethal step up. Other previous concepts are given a fair treatment as well, of course, with spell-stealing in particular a theme I've spotted in at least two descriptions.
I'm going to treasure this purchase as long as I play Pathfinder. It's exceptional in both form and function. I admire both the publisher and their inventiveness, and I'd recommend this to any Pathfinder group that would even consider 3rd-party.
[5 of 5 Stars!]