Terry Pratchett is an insightful master of satire and literary/historical allusions. I can't help but feel that categorizing Prachett as "fantasy" is misleading, because there is much much more to his work than wizards and trolls; the fantastic elements serve as a background more than anything else, while the meat of his work focuses on much more universal themes.
The Truth is the first Pratchett novel I ever read, and remains a favorite after all these years. At first I was a bit hesitant by the suggestion - after all, I really have no interest in reading about dwarves and elves and things of the like - but I was pleasantly surprised by what I found. Although there are several elements of "traditional" fantasy in Pratchett's Discworld books, the motifs are as much a part of his larger satirical work as the "main" subjects. You can take nothing in Pratchett's novels at face value, and his work is a delight for literature enthusiasts (I remember studying obscure 18th-century literature as an undergraduate, and stumbling across a reference to some of the same texts in a Pratchett book I happened to be reading).
The Truth follows a hapless William de Worde as he accidentally becomes involved in the publication of Ankh Morpork's first newspaper. Pratchett creates a world of fabulous characters as he examines how something as pedestrian as a newspaper can change the political and social landscape of a society - for better and for worse. He tackles subjects such as wealth and privilege, politics, and racial prejudices as he effortlessly satirizes all elements of various social institutions. No one is safe from Pratchett's scrutiny and wit, and the result is a truly entertaining and intelligent novel.
For those who are unfamiliar with the Discworld novels, I always recommend The Truth first. I really feel that it has something for everyone, and serves as a wonderful introduction to Pratchett's style while delighting audiences of all kinds.