This pdf is 37 pages long, 1 page front cover, 1 page editorial, 1 page SRD, 2 pages of advertisements, leaving 32 pages of content - quite a lot for the price!
Just about every DM had encountered a critter and ad-hoc added some kind of quality to the critter on the fly to make the foe more interesting - I know I try to give every monster some kind of memorable ability. This essentially is where this pdf comes in - we get a whopping 101 templates to add to your creatures, presented in the simple template format we already know from Paizo's book. It should be noted, that these templates range from rather simple to complex. One difference from RiP's Book of Monster Templates (which every DM should own) is that the templates can potentially be added on the fly to the critters. We don't get sample monsters for the templates, either. However, we do get some templates that go quite a bit beyond what anyone would consider simple.
After a short paragraph introducing us to the templates, we are cast right into these new templates: Many of the templates come with both quick rules and rebuild rules, the former being easily applied on the fly, while the latter often produce a more complex experience. From rather simple, basic templates like one granting the adhesive template (and a fitting extraordinary quality) to a creature to truly complex ones, we get a lot of fodder: Ever thought that banshee-style keening should not be limited to extremely powerful undead creatures? There's a template for it in this book! Need a creature touched by eldritch abominations from beyond the stars? Go for the creepy beyondling template! Want crypt guardians in vein of the Crypt Thing? There's a Crypt thing template!
Especially if you're a fan of Monte Cook's classic bestiary for the Iron Heroes d20 variant, you'll find some stellar adaptations in this tome: The Twin-bound creatures make a return and the hungering darkness also has its inspiration from one of the best creatures in said tome. This does not mean that content is ripped off, mind you, but rather that the pdf pays homage to one rather underutilized, awesome tome and brings the best of the ideas therein to PFRPG.
If you want, you could also create a beast that serves as an icon to one faith or even a walking fortress: Make a creature colossal and recreate a beast akin to legendary Dungeon adventure "Beast of Burden". Never start a high fantasy war without this one - the iconic potential is immense.
It should also be noted that the pdf offers a wide variety of 12 templates that reduce CRs from -1 to -5, which is plain awesome to create extremely complex creatures with multiple templates even at lower levels or have your PCs fight a taste of things to come, foreshadowing the true threat with great effect.
Editing and formatting are very good, I didn't notice any significant glitches. Layout of the pdf adheres to the full color 2-column standard by RiP and the stock artwork fits the theme. The pdf comes with alphabetical bookmarks, though I would have enjoyed more extensive ones. This is one of those books you really should own as a GM - you get 101 cool tools to use to make sure that your PCs don't get bored by fighting the oomphteenth monster xyz from the bestiary. How the creatures acquired the templates makes for seeds in and of themselves and while the templates are not as complex as in the book of templates, Designer Steven D. Russell knows templates and how to craft truly ingenious, cool templates that will enrich your game for quite some time. Additionally, we get quite a lot of content for the price and in the end, I don't have anything to complain about. Personally, I enjoyed the more complex template, but using the simple ones on the fly makes this book even more useful than anticipated. I recommend this book to the PFRPG-DMs out there with this piece of advice: Put this pdf down next to your adventure and every time you see an encounter you consider bland/boring, flip through these pages - chances are, you'll find some interesting template to make your encounter memorable. Due to the extreme usability, excellent bang-to-buck-ratio and the great ideas herein, I'll settle for a final verdict of 5 stars.
[5 of 5 Stars!]