Pratchett created a wonderful character: Death. You just have to love every encounter with this guy. Each dialog sparkles with this unique dry sense of humor that is one of the reasons I like Pratchett's work.
Death appears in almost all Discworld novels. Mort, however, is the first book in which Death is one of the main characters and has more “page time” than otherwise.
Mort is definitely one of my favorite Discworld novels.