This is, easily, my least favorite of Dick's books. I think it is poorly written, populated with uninteresting characters who are impossible to empathize with, and the premise just isn't that interesting. Being written in 1969/1970, you can tell that Phil was at a low point here. While his books are sometimes sad, and deal with themes of depression, they are almost always filled with a sense of hope. I feel as if Dick is pointing us in a direction that we need to look, a direction his characters can't often see. Maze of Death, on the other hand, is totally misanthropic. It's as if Dick hates his characters here. I was constantly reminded of Harlen Ellison's I Have no Mouth and I Must Scream, only Dick's book isn't as well written or interesting as Ellison's.
There are only three Dick books, of the ones I've read thus far, that I actively dislike, and Maze of Death is the one out of these that I hate the most.
/opinion