Probably what confused me most about this book was its repeated insistence that stories aren't real and the real world doesn't follow story logic. Just as an example, in a story the third and youngest son who goes on a quest that his older two brothers have gone on and failed is guaranteed success because that's how stories work. In real life, the third son probably has no better chance than his brothers unless he has some sort of extra knowledge or an extra talent. Possible, yes, but definitely not guaranteed in any way. And in this respect I feel like the book is in conflict with itself because the characters openly state that the real world doesn't work like stories and they have to write their own destiny because the story won't help them. Despite the fact that in other books like Witches Abroad it is very clearly stated that the Disc runs on narrative causality and people get shaped by the story-magic that dominates the Disc. Granted, this being Discworld there are subversions of the archetypes and tropes, but the stories still follow a familiar format. Heck, in The Last Hero Cohen and his Silver Horde succeed because they know how to manipulate the power of stories to their benefit. For the characters to be fighting against the forces of narrative, and at the same time benefiting from them, it made the book feel almost schizophrenic.
I also got the impression that the plot of this book ran along rather quickly and didn't really pick up until maybe a third of the book had gone by. This impression may be because I read this book rather quickly, but there was definitely a lot of time establishing the premise of talking rats and a talking cat who are all sapient before the real plot of the book got underway.
I will admit that this book was actually rather dark in tone, but I think it was still appropriate for children and definitely for young adults. I think it's also a reference to original fairy tales where the wicked are punished mercilessly and there's plenty of blood and gore. Granted, not a lot of blood and gore in this novel, but there are some pretty scary things in there too.
If the book didn't explicitly take place in Uberwald, I wouldn't categorize it as a Discworld book. And even then, the Uberwald in The Amazing Maurice is not the same as the Uberwald in The Fifth Elephant. There are no vampires, werewolves, Igors, or dramatic thunderclaps. It just...happens to be in a vaguely German village. But it's still an enjoyable book and I'd recommend it for fans of fantasy, but don't get your impressions of the Disc from this one book.