This is now one of the essential books in my toolbox. You can use this book in many different ways. You can use the book in it's entirety, and practically turn your D20 games into a totally new tactical game. Or, you can simply pick and choose the parts you like the most and plug them into your game. I'm falling into the latter. I'll be using the martial pool mechanic (for both attacks and defense), and incoporating the rules for weapons characteristics (traits that make weapons work the way they were designed to work: i.e. damaging armor, etc.). If you want to add a healthy dose of "realism" and era appropriate combat to your games, this book is for you. If you want to seriously expand the tactical spectrum of your game, then this book is also for you. If you are just your average DM, happy with your game, but maybe interested in some interesting plug and play ideas and concepts to liven up your game a bit, then this book even works for you. If you are a 3E fan and a "rules tinkerer", this book is absolutely essential.
[5 of 5 Stars!]