Although I think every Pratchett fan should read this book, there isn't much story to it and probably only two groups will find it worth buying - the hard-core fans who have to have *everything* by him, and the parents of small children.
I fall into the second category, and, as such, would heartily recommend it to other Pratchett parents. A children's book that's enjoyable rather than tiresome to adults and that stands up to endless rereads is a treasure that a parent can't afford to miss. This is a superbly funny satire of the normal structure of a children's book, with some of the best illustrations I've ever seen. (I don't know who Melvyn Grant is, but where *was* he when the illustrations were being done for the covers of the other Discworld books? His fantastic blends of realistic-looking characters and fantasy-dreamworld leave Josh Kirby standing. I hope this guy is hired for every new edition in the future.)
Like one of the other reviewers, I would also not have read this book to a child. My husband thought differently, and so, it turned out, did our son. When my husband introduced him to the book at the age of 21 months, he loved it. And, no, he hasn't started saying 'Bugrit' yet.