This book was famously withdrawn from the Hugo awards shortlist by its author, on the basis that he wanted to relax and enjoy the WorldCon. It's impossible to know how well it would have done; it's a very different book from the five that were actually on the list. His personal popularity, plus the fact that none of his novels had previously made it to the Hugo shortlist, would certainly have gained him a large sympathy vote for his entire œuvre, not just for this book.
I would still have voted for ianmcdonald, but nonetheless, this is a good book, one of the best of the Discworld series. The basic plot is that Lord Vetinari appoints a petty criminal to run the Ankh-Morpork postal service. He invents stamps, and must confront the "clacks" semaphore signallers, in one of Pratchett's better characterised narratives of personal redemption.
The background of Pratchett's well-established fantasy world, undergoing its own sort of industrial revolution is further developed; the clacks system combines the failings of post-privatisation British railways and telecoms. As well as lots of golems and the first proper banshee of the Discworld series, we encounter more human weird creatures in the form of Discworld's own versions of philatelists and phone phreaks.
And the whole thing is leavened by characteristic flashes of wit, such as the minor goddess Anoia, whose field of operation is Things That Stick In Drawers:
Often, but not uniquely, a ladle, but sometimes a metal spatula or, rarely, a mechanical egg-whisk that nobody in the house admits to ever buying. The desperate mad rattling and cries of 'How can it close on the damn thing but not open it? Who bought this? Do we ever use it?' are as praise unto Anoia.And then the punchline:
She also eats corkscrews.How true.