Given that there aren't many books out there, this is probably one of the best. However, it didn't meet my needs as it spent much of the available space "selling" me on how to use a rules engine and not enough on specific, "atomic", example code. I've been using JRules (IBM/ILOG commercial BRMS) for six years now and I am looking for an open source alternative as that product is essentially out of reach for the Small to Medium sized Business (SMB) due to the way it is marketed. I don't need "selling" on the value of BRMS technology to developers and businesses. I've lived it first hand. BRMS's will be to the coming generation what DBMS's were to us back in the 80's. Drools looks to be the odds on contender for winning developer mind-share but the issue at hand is helping developers get over the initial learning curve. So much of this kind of book tries to do too much and ends up being like trying to learn to fly using a 747 instead of a Cessna. What we need are some basic books on "flying" BRMS's. For example, instead of using a full fledged system as an example, it would be better to describe basic "flight maneuvers." Showing some simple POJO implementations of BRMS for replacing the data validation code on a typical data entry form would be more immediately useful than trying to wrap your mind around a complete business system. The focus needs to be on some basic building blocks to "get your feet wet" with this specific product and ignite interest via early experience. I'm afraid many developer's will lose interest because they have to wade through too much "set up" to get to any "reward." This book, while valuable, falls short and is typical of the approach that seems popular among many approaches to BRMS education. When learning to "fly" you start with basics and then combine them into more complex scenarios. This book would be much better if it started with small self contained building block scenarios and built from them. Instead, it starts with a complete project. Too much time ends up being spend on outlining the "project." As developers we are already looking for a better solution for implementing the "model" and "controller" pieces of our MVC work. We don't need to spend time being convinced of that. I'd like to see a book for this product that was written more like a basic flight primer. You want to give that prospective "pilot" their first "ride" and get them hooked on actually flying. This book is too much like just buying a ticket on a commercial airline and watching someone else fly than getting your hands on the controls. It won't do nearly as good a job of attracting "new pilots" to this technology as it could have. BRMS technology has been around for a while but only the privileged few have really gotten to fully taste what it can do for you. It will likely be the "next big thing" in software development and Drools, like MySQL, PHP and other "freely" available technologies stands poised to be "discovered" by developers that really need to get into this genre to go to the next level in their development. Unfortunately, this book falls short in giving them what they need to quickly get going with Drools by trying to cover too much theory and not enough simple practice topics (like simple form validation code.) There isn't much out there yet so it's better than just trying to read the on-line docs but it doesn't leave you feeling like you could start writing code in your own projects. That's the big gap as yet unfilled in this genre.