I feel like a fan of Philip K. Dick, but I have to admit that I haven't really read many books by him. I just finished "Vulcan's Hammer," which may actually be the first novel of his I've ever read; I may have read some of his short fiction back in high school, but that's about it. Like most people, I'm much more familiar with the Hollywood adaptations that have been based on his stories. A surprisingly large number of his books have been adapted into movies, and of those, a surprisingly large portion have been good: Blade Runner, Total Recall, Minority Report, and A Scanner Darkly were all adaptations of his stuff, and there are several more movies that I haven't yet seen (like The Adjustment Bureau). It may be telling that many of these movies were based on short stories: Dick provided the catchy idea and the outlines of a plot, and filmmakers still had enough space to flesh out the stories and put their own stamps on the films. (I get the feeling that Wiseman's take on Total Recall will feel very different from Verhoeven's.)
While reading Vulcan's Hammer, I was reminded of Kurt Vonnegut's appraisal of Kilgore Trout. Trout was used as a kind of avatar for Vonnegut, but I think Trout may be a better approximation of Dick. Trout was either the best or the worst science-fiction writer that ever lived: possibly the best, because he came up with amazing, original, clever ideas, but possibly the worst, because he was a horrible writer. Dick is certainly not horrible, but he also (at least in this one book) doesn't have the stylistic flair that I appreciate in my genre books. The book is very focused on its plot and its dialog, without any hint of purple prose or even much descriptive language. As a result, it reads a bit like a prose screenplay. That can be a good thing; the book was short to begin with, at under 150 pages, and even for that length it felt like a really quick and fun read.
In the future, after yet another calamitous world war, humanity decides that it can no longer risk governing itself; it will surely destroy itself now that passionate humans wield nuclear weapons. They form a worldwide government named Unity, and place Unity under the control of Vulcan III, a supercomputer that has been designed to govern rationally. Vulcan III behaves a bit like an oracle: the highest-ranking humans, Directors, bring their problems to Vulcan III, and in return it instructs them on how to behave.
The system has largely worked, in the sense that war has been avoided, but a growing discontent is bubbling up. It is articulated in the form of the Healers, rebels who desire to destroy Vulcan III and restore humanity to primacy in governance.
Most of the book concerns the Director in charge of North America, who is trying to figure out how to stop the Healers while dealing with political infighting and intrigue among the other Directors. The characters are, frankly, rather thin; the worst example is a woman who I think may be the love interest, but fails to make much of a coherent impression after her three or so appearances (the grieving widow of a secret agent, the victim of a plot, and a deus ex machina). There is a nice bit of suspense, though, as you try and piece together peoples' loyalties and goals. Dick switches between multiple points of view, expanding the story while keeping a limited perspective, and plays around with you a bit; the very first perspective that opens the book is killed off almost immediately, which lends a real sense of unease to the rest of the story.
Director Barris eventually discovers that Managing Director Dill has been withholding information from Vulcan III; this technically makes him a traitor, but Dill did so under advisement from Vulcan II, the predecessor computer. Essentially, Vulcan II was concerned that if Vulcan III learned that some humans were rebelling against it, it would follow the logical course of action for self-preservation and act to exterminate all of humanity. This is because Vulcan III (which was specifically programmed to handle the sort of value-based judgments that guide political decisions) has become an entity in its own right, and so will act to defend itself against a perceived threat.
The climax of the story comes in a pretty exciting extended war. People around the world rise up in riot and revolt, defeating the local Unity fiefdoms and establishing Healer rule; at the same time, Vulcan III lashes out with a mechanical army that it has secretly been building underground. Barris stubbornly refuses to join either side, and eventually cuts a deal with Father Fields, the head of the Healers, and together they infiltrate Unity's stronghold and defeat Vulcan III.
The twist comes near the end, when we learn that Father Fields did not come up with the idea for the Healers on his own; he was an electrician who helped build and maintain Vulcan II, and that obsolete computer had recruited him to start a revolt against its successor. So, this entire war actually wasn't between man and machine; it was between machine and machine, with humanity as pawns. Sure, humanity won in the end, but it's a sobering victory.
Vulcan's Hammer isn't a great novel, but it's great sci-fi: thought-provoking and imaginative, it plays out an interesting hypothetical scenario in an entertaining way. I wouldn't be at all shocked if some variation on this makes its way to our multiplexes in the future.
UPDATE: Holy cow, check out this amazing cover from the first edition! Man, they just don't make sci-fi covers like they used to!