It's difficult to describe just how valuable this book is to a hard-working Dungeon Master. Instead of floundering helplessly with a dozen Monstrous Compendiums, this book gives you over 600 monsters, with complete details! And that doesn't just mean combat statistics - diet, motivation, appearance, culture, and more are all touched upon. There are of course limitations to the presentation, but the text is admirable because it is evocative - the "mysteries" of each species encourage the DM to elaborate as much as he or she sees fit. The one drawback to this book is the illustrations - the quality of many of them is abominable, which is a shame, considering the power of the text. But, if you can overlook that flaw, this book is a must have!