It is a very good book set in a world where the Axis powers won the second world war. It focuses on ordinary people of no very great importance trying to understand their situation.
The novel is alive with ideas. They complexly interact with one another. In part it is about evil and that evil which is about pure destructiveness born out of madness, but it is also about the process whereby people who do not share that madness, come to accept at least parts of it. It is about fate and approaches this through the use of the I Ching by characters in the book. It is also about alternate possibilities and the impossibility of knowing what would have happened if things were different. It is also to some degree about the nature of reality and mysticism. All these topics are sophisticatedly treated and interact in complex ways.
The book is very human and humane. There is something odd about Dick's prose, but it works well for the most part. This is my second Dick novel and it is clearly better than Do Androids Dream of Electric Sheep, although that novel is good as well.