All I need to say to recommend this book, really, is to mention that Terry Pratchett wrote it.

It’s ostensibly a Christmas book, in the same way The Nightmare Before Christmas is ostensibly a movie about Christmas.  When the Discworld equivalent of Santa Claus goes MIA, Death fills in for him.  Hilarity ensues.   And dang it, the guy manages to sneak in a reference to DOCTOR.  In a fantasy novel about Christmas.