The publishers deserve to be congratulated on getting so many games designers to participate in the project.
If you buy this book with the idea that it will turn you into an instant millionaire by showing you how to convert game ideas and programming skills into marketable products you will be expecting too much. This book is rather like well-edited Internet chat-room sessions with various experienced people from the computer games industry swapping insights and ideas. However remember that no games' designer is going to give you any real trade secrets.
If you are thinking about game writing or simply looking for a job in that industry I think this book is worth the time it will take you to read it. There are well over a hundred contributors and the principle editor has also gathered together a lot of useful information, even though it will come as no surprise that much of this is US oriented.
The publishers deserve to be congratulated on getting so many games designers to participate in the project.