This book is a brilliant product for aspiring fantasty/sci-fi writers and GMs/DMs alike. It contains sage advice on a range of different topics within the sphere of world creation, from stroytelling techniques to the design of environmental features, monsters, villains, and beyond. The tips and tricks provided are deceptively simple and straightforward, but in many cases reflect the kind of commonsense wisdom that can only be gleaned from years of adventure writing/game-running experience.
I have to give the product four stars out of five, however, because it contains a significant number of elementary typos and mistakes. One or two orthographical glitches lend a degree of character to a volume, but when a book's description indicates that the content has been authored by a plethora of legendary writers, the customer can expect it to contain nothing less than highly-polished prose. As a copy editor myself, I just can't see that there is any excuse for the number of errors that crept into the final release, which is a shame as it is the only thing preventing this book from being truly exceptional, as opposed to merely very good. In the end it is only a minor irritation, though, and the content is (as indicated above) stellar.