This book discusses Ayahuasca from a variety of perspectives: historical, religious, chemical, cultural, horticultural and experiencial. The way the book is structured it would be easy for a reader to skip over the topics that don't interest them. All of the information is presented in a thorough, well-written, and objective manner offering some conclusions while at the same time allowing the reader to form their own.
Most interesting were the 25 or so personal accounts, 3-4 pages each written by people who appeared to Americans/Westerners who took the drug for religious/spiritual purposes and in a religious/spiritual setting. It was clear, based on their mindset (objectives and beliefs) and the religious setting that Ayahuasca seems to somehow create a religious construct through which a person can work through personal issues or sort through personal beliefs. The experience seemed to have a profound affect on most of these people.
Overall, I got the impression that Ayahuasca was not connecting these individuals to something divine outside of themselves, but rather that it was freeing the brain up to explore the subconscious/ID in order to resolve problems or explore issues in the persons life.
Well worth reading if you're interested in this sort of thing.