I love Terry Pratchett books, I really really do. They're brilliant. Pure, unadulterated genius.
This book follows the story of a con artist as he tries, with the flair of a natural showman, to get the Ankh-Morpork post office up and running against the competition: the clacks, semaphore towers which can send a message across country and next to no time, but are run by a bunch of money grabbers who don't care about the clacks themselves, only what the towers can do for them.
Old favourite discworld characters make small appearances. Vimes is seen, but not heard. Carrot and Angua pop in briefly for a chat, Colon loiters outside a building, the librarian is seen in the background. But the patrician....ahh...gotta love that man. Many of Ankh-Morpork's inhabitants seem to forget that he is actually a tyrant, and therefore doesn't have to justify himself to anyone. And there are the golems, and they always make me smile.
You've got the fantastic clash between the bad guy and the bad guy. The bad guy who really is a good guy, just not interested in honest work, and the bad guy who appears to do honest work, but really is a bad guy.