How can one rightly deduct a star when the book in question performs it's intended purpose and confirms to the reader whether its subject is the right solution for them? Any author can tell you that some particular choice solves all the world's problems, but it is less common to find a book which actually tells the reader the downsides of its subject and how to determine whether it suits your particular need and personality or not. In that regard, then, this book certainly succeeds. It tells the reader exactly what is involved in the construction, what kind of performance to expect, and how much maintenance is realistically involved. That seems worthy of an addition star to me, even if I never build a rocket stove. Would you drop a star from a book about sky diving because you decided you didn't want to jump out of an airplane?
This book does a fine job of explaining the concepts of "rocket" style wood stove design and construction. This 2nd edition also includes reports from individual designers and users, which I tend to find very valuable as it grounds the material in real-world applications. The book covers all important concepts in detail and admirably explains which dimensions are important and which are less so. I found the step-by-step pictures to be invaluable to helping the reader actually build their own stove, but I also found some of the descriptions and associated diagrams to be confusing. A few things that were included in diagrams were not well explained or at least not well understood by this reader without multiple readings. To the authors' credit, however, some of the details are difficult to describe with words. I also found that while the authors do a good job of telling the reader the potential dangers of a positive-pressure flue system, they didn't describe their own methods for sealing metal duct systems.
In short, this book would be extremely valuable to those contemplating a wood heating system of any type, but it is a must for those seeking 90% efficiency from a wood-burning appliance for home heating. Masonry heaters can often match this efficiency (see The Book of Masonry Stoves for more), but they start at about US$10,000 and typically require advanced masonry skills. I have a personal affection for masonry heaters with glass viewing doors and top ovens, but a rocket stove is much more accessible for a do-it-yourselfer and is more versatile to fit both fast radiant and slow mass heating needs. Whole-house masonry heaters can't heat up quickly, which could matter to people that are away from home for long periods. Rocket stoves can heat you up rapidly while still offering substantial heat storage, if you build them to do so. They are certainly worth your consideration and this book is written by the world's foremost fiddlers with Rocket Stoves. This 2nd edition still comes across as a work in progress, but Rocket Stoves already have proven themselves to be long-term, efficient solutions to many heating needs. With this book in hand, virtually anyone can build their own heating solution powered by a renewable resource.