This is not a Terry Pratchett book in the normal sense. Reading this after the others is like moving from the west coast to the eastern seaboard of America, and finding the pace of life taken more seriously with a more european attitude. It is also like watching a favorite sitcom in which the producer decided for a change to take the canned laughter out, presumably because he is confident of the writer's ability to write comedy that stands on its own. I would have thought that I'd have been pleased to see a Pratchett book without the rampant, incessant sillyness, but the truth is it shows Terry Pratchett to be only an ordinary fantasy writer, and I don't like straight fantasy.
Nor is this a Discworld novel in the normal sense. It says it is on the front cover, but since there are no wizards, or Death, and given the lack of hilarity, it could actually take place in a totally different universe to Rincewind's.
A girl decides to pretend to be a man, and joins the army to find out what happened to her brother. She becomes part of a posse made up of vampires, trolls, etc, and they go to war without any training. It transpires through the entire length of the book that the entire regiment are actually women dressed as men, and so too are a good number of the army's senior officers. The comedy is that thin.
The only part of this work that holds any interest to me is Terry Pratchett's treatment of religion, or rather on the perverse ways that people respond to religious issues, sometimes using it as an excuse for war. It is clear that Terry himself is apathetic, and that he does not understand (nor wishes to tolerate) the motives behind some of the more extreme groups in our world. Thus he creates a fictitous god and religion against which he can blaspheme as much as he likes (and does).