I recently purchased the bestiary and have finally had time to really look it over. It's 139 page book of monster goodness for the fantasy AGE game using the AGE rpg system by Green Ronin publishing.
Pages 4-124 is the bulk of the book, with just shy of 60 monsters. Each monster taking up two to three pages. Each entry has a very full description, A well layed out set of game stats, and a beautiful full color picture. The absolute best part in my opinion is the Adventure hooks. Two to three Adventure hooks per monster.
Pages 127-132 is beasts and animals. Entries from beasts of the land, sea, and air. Very well layed out.
What makes this book really shine is the focus on customization of monsters to fit the GMs needs. Pages 133-138 is all about how to do that. All about how to add qualities to customize your monsters. Page 3 has an entry for beefing up adversaries, how to make elite, heroic, and epic versions of each monster.
I really like that the Fantasy AGE bestiary has such a strong focus on Adventure hooks and customization. Great monster book, and a great GM resource.