I don't want to say bad things about this book - I've always loved Terry Pratchett and I know it wasn't entirely finished when he died. But it just doesn't live up to the other Tiffany Aching books. 
 Some of the new characters and ideas seemed rushed, the plot didn't tie together as neatly as it should - I was going along expecting it to and it never quite got there. I wonder how much of that was down to a desire to get as many as possible of the old favourite characters back onto the page in some way, a last hurrah of sorts. The showdown lacked the sense of danger you'd expect - especially if you've read Lords and Ladies (or even the Wee Free Men), where the elves were a much more menacing threat. Even the usual Pratchett humour was like a pale imitation of itself. 
 Sorry. 
 I'd say read it anyway, as the conclusion to both a wonderful series and a wonderful career, but don't go into it expecting it to be to the same polished standard as his earlier books. 
 Oh, and Terry Pratchett does not translate well to eBook format. The footnotes are always one of the best, funniest parts of the book, and in an eBook (at least in ePUB format) they come at the end of a chapter instead of the bottom of the page, so you lose the thought process that made them so funny in the first place.