Whoa man, this book is, like, deep.
But seriously, there's a lot going on here. The overarching theme of real/false realities (including a weird and interesting scene where Tagomi completely trips out and catches a glimpse of "our" world) and what that even means was fascinating and, I'm now beginning to understand, classic Philip K. Dick. This man was the king of the paranoid dystopian novel, most likely because he was actually that paranoid.
There are a number of very interesting devices used in this book. The obvious one was the frequent use of the I Ching, both by the characters in the novel and by Dick himself while writing the novel (a technique mirrored by the character Abendsen, who wrote The Grasshopper Lies Heavy, the novel-within-the-novel). A unique and potentially risky approach to take to writing a novel, one reminiscent of paper-and-dice RPGs. In my opinion, it worked out in Dick's favour. Another notable device was that of using a truncated English-second-language style patois in the narrative voice of the characters living in the Japanese-ruled P.S.A. At first I found it off-putting, seeming like there a lot of deleted words, but then I realized what Dick was doing and it started to flow a bit more for me. There's more, too. The underground economy of counterfeit Americana, the Nazi politics, the gender struggles, the racial inequalities...a lot going on.
Dick's main concern, though, wasn't any of the stuff that more commonplace writers might have focused on. His sights were set on the weighty question of what is real, who defines reality and why, and does the distinction between true and false reality have any actual significance? And, as usual, he offers us no answers.
And that's why he was great.