Used this as part of my daily devotional. There are 80 short chapters on prayer, most just 3 or 4 pages. It is just perfect to help inspire you to more prayer.
I spent months slowly working through it. I know about six or eight of the authors. But there is pretty wide range of quality and insight in the book. It is an attempt at creating a real textbook on prayer. I think it was a valiant attempt. The weakness is both the wide range of writing (creating a lack of cohesion)and the lack of depth into any of the particular areas.
Unfortunately my dogs ate the book a few chapters before I finished.