Is this my cow?
What I loved most about the latest Discworld book (Thud! for the uninitiated), were the bits where "the world went soft and pink". Every time Sam Vimes interacts with his son, I know that Pratchett is a truly great writer. And every time Sam Vimes fears for his son's safety, I know that Pratchett is seriously overdue for the Booker.
However, there is a however. For example, I found too many superflous characters in this book. Also, the plot is too complex (even though the theme is certainly topical and important) and it relies on too many external elements for both micro- and macro-resolution (as opposed to some of Pratchett's better books, where resolutions come from within the plot).
A good book, but not a good Pratchett.
All in all, that is not my cup of cow.