The sparks just didn't fly this time for several reasons: One is that I love the City Watch somewhat more than Vimes. Don't get me wrong: I adore Vimes but I love the cast of characters in them. All of them. So seeing most of them only for one or two scenes was disappointing.
Then there's the simple fact that it contained most of my least-favourite (crime)-novel tropes. I'm not a fan of 'policeman stumbles over corpse on his holidays' for a variety of reasons. Just let the police there do their job...but they're conveniently corrupt/incompetent (well with one exception). Tropes that annoy me the 2nd.
Then there is The Big Bad who is Just Plain Evil. He also outsmarts everybody...except Vimes of course which makes for a somewhat boring finale.
Last but not least the morals is delivered somewhat...heavy-handedly. As in it hits you over the head with a large brick. That is attached to a telegraph-mast. That is attached to a medium-sized house. Of course he deals with a very serious topic here but I read Discworld-books where serious topics were discussed in a way that did not make me feel like every other sentence is "And this is really horrible, you see."
This leaves us with a below-average Discworld book...which is still an OK-ish book because it's still Discworld and I love Vimes and Lady Sibyll and Little Sam is quite adorable. But I don't see myself re-reading this anytime soon.