One of the greatest novels of th 20th century. I've been a PKD fan since the early 1980's, obsessively collecting his work, most of which at the time was out of print. It's safe to say that no person did more to shape my intellectual development as a teenager than Philip K. Dick. I am forever in his debt.
That said, TMitHC is a treasure. It distills a number of Dick's obsessions into a taut character study set against the backdrop of a world going even more mad. Each of the 6 'protagonists' here are searching for truth. Only a couple of them are capable of facing it dignity.
As with all of Dick's best work the world-building is efficient and brilliant. I re-read this recently to prepare myself for watching the new serial, and was reminded of just how good Dick's prose is. The casual racism of Mr. Childan, the inner strength of Juliana, the coldness of Joe Cinnadella. But, it is Mr. Tagomi who owns this novel. He is one of Dick's finest characters, at once pragmatic and idealistic. Mature and naive. The living embodiment of the Tao.
The ending matters both textually and thematically. It separates the characters into those who can face the reality of their world and those who cannot.
For those looking into PKD for the first time I highly recommend these books over all of the others (in my order of preference): 1) Ubik 2) Do Androids Dream of Electric Sheep 3) The Man in the High Castle 4) Flow My Tears, the Policeman Said 5) The Three Stigmata of Palmer Eldritch 6) Clans of the Alphane Moon 7) A Scanner Darkly 8) Martian Time-Slip 9) Dr. Bloodmoney 10) The Transmigration of Timothy Archer
Others like Time Out of Joint, The Game-Players of Titan, Now Wait for Last Year, The Penultimate Truth and Galactic Pot Healer are fine diversions, but the books above are essential. VALIS is a difficult mess of a book. Timothy Archer is the only one of the 'trilogy' I actually enjoyed as a narrative.