Terry Pratchett has long been known (and admired) for his considerable ability to make anyone and anything a satirical target. He has taken on the police force, Death, and every conceivable political institution know to man. The Powers That Be, of course, are the only target left. And boy were they hit hard.
Teamed with the uber-talented Neil Gaiman, Pratchett has taken the wit and wisdom of his famed Discworld series and applied it to the end of the world. The result is one of the most brilliant books you will ever read.
The story of Good Omens follows a variety of characters, the principles being Crowley (a demon who has "gone native"), Aziraphale (an angel who has pretty much "gone native" as well), and Adam, the Antichrist, who was mistakenly switched at birth and has grownup away from the influence of Good and Evil. The Apocalypse has been right on schedule, until Hell realizes that the aforementioned Antichrist is not where he is supposed to be, and Crowley, now the focus of a great deal of blame, must find him. Of course, Pratchett's trademark humor is found throughout the book. The demons and angels have decidedly human qualities (Crowley attempts to enrage humanity into sinning by jamming all cell phones in London for example), which not only exposes our own flaws in a humorous way, but also adds to the appeal of the characters. Everything from poorly-made foreign cars, to bikers, to the entirety of Manchester has been lampooned with satirical perfection and when you aren't laughing at the subtle humor, you are marveling at how well the plot flows and the sheer variety of characters portrayed. Fair warning - if Douglas Adams and Monty Python have never been appealing to you, you will probably not "get" this book. For those of you who are so enlightened, however, this comes with my highest possible recommendation.