Not my favorite Discworld book by a long shot. Too many sideplots that didn't add anything to the main narrative (or entertain in and of themselves). I'm also not very fond of Moist as a protagonist, I think because I don't really understand what drives him. Okay, yes, he craves excitement, but that's fairly shallow characterization compared to Vimes or Brutha or William. He's kind of the anti-Rincewind, and I've never been a huge fan of the Rincewind books either.
The ongoing descriptions of a Certain Character's health problem made this the third piece of fiction in a lifetime of reading that's squicked me to the point of physical nausea. Which, on the one hand, props to Mr. Pratchett for his power of description. But on the other hand--eww.
Still, even the worst Discworld is better than a lot of what's out there. It was a smooth and mildly amusing read. It just lacked substance.