To open, if you picked up this book because you like the amazon webseries--particularly if you have no previous exposure to Philip K. Dick--you will likely be disappointed. 
 This is not an action book. The pacing is sedate, the focus is on ideas. There is no Resistance movement. The world is a terrible and authoritarian place. People are not generally pleasant or likable. Reality is questionable. 
 In short, it's a PKD special, and I have nothing but applause for its excecution. 
 The most chilling part about the world PKD presents to the reader--a world in which Germany and Japan won WWII--is most chilling not because there are Nazi's in power (in all honesty, you see much more of the Japanese) but because, for most of the characters in the book, who won the War doesn't really change anything. 
 Certainly, most of the characters agree that the Reich is a mad institution--the atrocities in Africa, the labor camps and more are all repeatedly mentioned--but the systemic racism at all levels of the society presented goes generally unremarked upon. It is uncomfortable--not because it is so outrageous--but because it is so familiar. Those things that the reader is presented as the greatest madness of the Reich--the ubermensch mentality, the godlike ambition--are equally familiar to readers past and present. Right down to Operation Dandelion, which--in its own way--occured as part of our own history. 
 PKD forces the reader into the supremely uncomfortable position of questioning whether the outcome of the war actually made a difference, both through the subversive nature of the novel, and also through the self-referential novel-in-a-novel The Grasshopper Lies Heavy. 
 Our history has been written such that the Allies (particularly the USA) are portrayed as universal good, and the Axis (Particularly Nazi-run Germany) as faceless and unfathomable evil... but that is a distortion of the facts. Even now, almost 54 years later, PKD calls us out on that ever-so-popular American myth. 
 There's more to be said, of course, there usually is. But better and more scholarly minds than my own have tackled this book, and after deeper reading. 
 Needless to say, I recommend it.