This book has just be reissued as part of the SF Masterworks series, and is not among his most well-known works (such as "Do Androids dream of Electric Sheep", "A Scanner Darkly","The Man in the High Castle" and "Ubik"). It was written in 1970 when Dick was undergoing a sort of religious conversion and much of the ideas expresed in the book are as a result of his relationship and discussions with Bishop James Pike.
The book contains the usual Dickisms such as paranoia, hallucination, distintegration of society/environment, heroes in low-grade maintance roles and the recurring one-dimensional portraits of female characters as either selfish, controlling or oversexed.
The book is far from perfect, but, as anyone who loves this author knows, that isn't the point. The point is to enjoy the warped ideas, lunacy and sheer strangeness.
The plot starts off as a murder mystery (one of the lead characters is suprising offed early on) and reads a bit like a SF version of "And Then There Were None" on drugs. It does move into more usual Dick narrative territory as the story proceeds. Not wishing to give away the ending, lets just say that it has overtones of a recent SF blockbuster film. (Even films not based on his books owe a large debt to him)
Enjoy another great addition to the SF Masterworks collection...!