In this latest (and last?) book in the Tiffany Aching teen series, a dark and evil presence has spread through the country, creating ill will for witches. It's not enough to just help the elderly and infirm as a witch; it'll be Tiffany's true test and coming of age to conquer the darkness.
While the Nac Mac Feegle still provide a bit of comic relief, this book is darker than the others in the series. Tiff's about at the end of her rope - worn out and weary from too many long nights and missed meals. Just when she's at her worst, this dark force begins stalking poor Tiff. She's already proven herself to be a powerful witch - can she take one more challenge?
There's not as much dramatic tension in this book - the final battle is great, but it lacks a big buildup throughout the book. More, this book provides a glimpse of the day-to-day, overlooked jobs (like clipping toenails) that really make up Tiff's job - it's not all kissing the Winter and saving kidnapped boys!
I liked the book, and it could be a fitting conclusion to the series. I wouldn't recommend it as your first Pratchett book to read, but it's a great story none the less.