A terrific edition to a ToC: Bookhounds campaign, The Book of Smoke is both an interesting source supplement and an in-game artifact. As such it has a ton of potential. About the only down side is that to get the most out of it, you really need players to read the book and we GMs all know how difficult it can get players to read even short summaries. However, for the right group, this book is pure gold.
[5 of 5 Stars!]