Only PKD can take the element of time travel to a level that is not cliche. As with some of his other sci-fi books, you tend to forget you're reading science fiction and find yourself just reading brilliant fiction.
Dr Jim Parsons is in a car accident and finds himself in a future society. But is there truly a future, present, or past? Or do we all just live in a space that time alters?
The shupo's are like the young children of the Chinese cultural revolution. I don't think that was an accident on PKD's part. Read this book. Check your date. Wonder.