Dick's second best novel after Ubik. But most non-scifi readers are going to like this more than Ubik. Alternate history that points to actual history. The Germans and the Japanese have won WWII, it is the 1960s, and they are not too fond of each other. That's as much as I'm going to give you. The usual Dick theme of shifting realities. Very well drawn characters and a plot supposedly determined by the I Ching that leads to several interesting climaxes. Dick tends to be a bit dated now, pointing to the 60s and 70s for themes, culture, and language, but Castle isn't hampered by this like some of his other novels. This is a genre bender that I would only hesitantly call science fiction. Everyone I have ever recommended it to that hates scifi still loves this book. Despite the usual Dick weirdness at times he tones it down and maintains coherence enough to appeal to the non-genre/non-Dick fiction reader. Just enough for Dick fans, but not too much for the rest.If you are mainly a hard scifi fan, Dick is going to be a tough pill to swallow. He utilizes the usual scifi tropes at times but doesn't really care how consistent they are and doesn't dwell on them except as necessary to get whatever his point or theme is across. He is primarily literary and only secondarily scifi.This is really a beautiful little novel and definitely in my top 25 books of all time. One of the VERY few books I would even consider reading a second time.