I loved Dick's novel and own both print and digital copies. If you don't already own it, buy and read it. While the book is a classic, this TV production isn’t. Though bearing the book's title, it would be more accurately described as a minimal adaptation since at least 90% of the film's events are absent from the book. The similarities are merely: the presence of Nazis, Japanese, and their occupation of America. Think of an old-time Western containing these elements and you won't be far off.
The spiritual elements ("wu"; I Ching divination) are absent or so slight as to be not understandable. If you haven't read the book, the series may cause headache arousing confusion. I was confused and I've read the book several times. I initially gave up watching this series in the middle of the first year's episodes, then returned to the second year and completed it since I love the World War II alternate history genre.
What I'm awaiting is BBC’s upcoming production of Len Deighton's 1978 novel, "SS-GB." This book is also in the World War II alternate history genre but of a traditional literature style and thus easier to follow than "The Man In the High Tower."