Nightwatch is my favorite Terry Pratchett novel. It is funny, as they all are, but this one has a bit more depth and meaning than a lot of the others. I am amazed that Each of Pratchett's novels seem to get better and better. A lot of authors seem to rest on their laurels a bit, especially if they have written a lot. For example, Asimov, Heinlein and McCaffery all got a bit silly towards the end, trying to combine all of their series' and getting all mystical and new age-y and similar things. Pratchett keeps getting better. His craft and how he writes keeps improving. It is very impressive.
I've got just one quote, because I wasn't paying attention to that when I was reading it, but I liked this one because it reminded me of Ryan:
Nightwatch. Terry Pratchett. Harper Torch. 2002
Vimes sighed. "Mr. Shoe, we don't have a file on you. We don't have a file on anyone, understand? Half of us can't read without using a finger. Reg, we are not interested in you." Reg Shoe's slightly worrying eyes remained fixed on Vimes's face for a moment, and then his brain rejected the information as contrary to whatever total fantasy was going on inside.