I enjoy the Terry Pratchett Discworld novels very much, and eagerly bought the latest Tiffany Aching book on Friday.
The first three Tiffany Aching books (The Wee Free Men, A Hat Full of Sky and Wintersmith) were aimed at younger readers, and this book is also nominally aimed at younger readers, although I've always felt like these were Discworld books that happened to be about a younger person (like Mort, for example), rather than books for children about Discworld.
Sir Terry Pratchett said: “This is an unusual book because the Tiffany Aching books began as children’s books then metamorphosed into young adult books and I Shall Wear Midnight really is the last book in which Tiffany Aching could still be considered a children’s character. These days there appears to be very little difference between young adult literature and adult literature. I consider I Shall Wear Midnight to be young adult literature with the added bonus that this book doesn’t have any more bloody vampires in it.”*
I enjoyed I Shall Wear Midnight very much. I've always had a soft spot for Tiffany, and for the Chalk, which reminds me of Sussex. It's hard to write about the book itself without giving away the plot but the theme is similar to that of Unseen Academicals - how we can distrust and be persuaded to turn on anyone that we perceive to be different to ourselves, and demonise anyone who is 'other' even if they are performing a useful function in society. The villain of this book is the Cunning Man - a spirit that whispers in the ear of people to magnify all their anger and petty jealousies (a bit like the Daily Mail).
*From the Waterstone's press release. To read the whole thing, see here http://www.waterstones.com/wat/images/special/pdf/pratmidnight.pdf