Dick is an ideas person. Like Electric Sheep, High Castle is full of ideas, all tossed in and scrambled fairly willy-nilly. A dozen great books or movies could be teased from the setting he creates. 
 Unfortunately, Dick is not an execution person. 
 There's very little that might resemble a plot. The alternative '60s are described in detail, but it's an empty world. The characters are soulless automatons who putz around for a bit and then we reach the last page and it's over. Dick starts three distinct plots: One is a political thriller/spy story that ends fatalistically (the immediate mission complete, but with the realisation that it will help nothing), one is a bootstraps story about the conflict between the antique industry (forgeries included) and the attempt to generate new culture, and the third is a sort of semi-lucid road trip that ends up being a sort of spy story of its own. 
 These stories sort of connect at points (someone from Story A knows someone from Story B, someone from Story B used to be married to someone from Story C), but that's about it. These stories, and the characters that make them up, are just there as vehicles for the world development. 
 And that world development is... meh. The transatlantic rockets are the kind of thing I'd expect from the Fallout franchise's tongue-in-cheek futuretech. The Nazis being awful, but also hopelessly inept and disorganised once push comes to shove because, ultimately, you can't run a society on hate is sad and scary in this era of the Alt-Right controlling the government, but ultimately unimaginative. 
 Then there's the dialogue. I'm guessing that Dick was trying to "Japanify" people's speech patterns? Frankly, that came off more Mickey Rooney than linguistically insightful. It was overplayed and overdone for my tastes. 
 I did like the recurring theme of The Grasshopper Lies Heavy - a fictional book within a book of fiction, about an alternative world in which the Nazis did not win the war. That was funny. 
 I also liked the discussions of colonial identity, from both perspectives. How do the Japanese react to colonising the pacific US, and how does the pacific US react to being colonise? How does the US break? That's all an interesting background theme that just didn't get the plot or setting it deserved.