I've read the book but not seen the movie. The book is good, but it is extremely dark and cynical. It's all about how drug abuse destroys lives, and there is even a "dedication" page in it where Dick lists a number of his friends who were killed or terribly hurt by drugs.
There are also heavy doses of social criticism and irony, about many topics. All the organizations that are ostensibly trying to eliminate the drug problems really just make things worse, either by design or by accident. For instance, in order to infiltrate the organization that produces Substance D, the government sets up numerous agents as dealers, to the point where half the dealers are really cops undercover.
One of my favorite quotes comes from the book. This is pretty much how I understand drug addiction (this is a paraphrase; I don't have the book in front of me):
"The best thing about being clean is that now, when I walk down the street, I see people. I see dogs and cats and trees, the sky and the clouds. Before all I saw was dope."
It's a good book if you aren't looking to have any fun and don't mind feeling depressed at the end. It's on a similar wavelength to "1984." Punishing, but relevant.
