I so wanted this to be the best Terry Pratchett ever. It isn't, but it ticks several boxes for me. It more or less rounds off the history of Ankh Morpork's ascent to the modern era with the arrival of the steam railway. Though Moist von Lipwig is the central character (and he's never been my favourite) there are glimpses of Vimes (who is my favourite) and a fair bit of Vetinari (and Drumknott). As the railway travels across the face of the Discworld we briefly see landscapes we know and love. It's a farewell piece. We don't get to say goodbye to the witches, however. Maybe that will happen in the, as yet unpublished, fifth Tiffany Aching book.