The Light Fantastic
A lot like the first Discworld book, but with a slightly higher ratio of laugh out loud moments. I personally found The Colour of Magic to be a little rough around the edges; not a badly written book by any stretch of the imagination, but lacking a certain amount of polish, where at points the brilliance of the madness would tail off a little. The Light Fantastic was very much like its predecessor in tone, but Pratchett had clearly developed a little as an author, and those slightly rough patches were less frequent. I still found the style of the writing to be a few blips short of the genius of, say, Douglas Adams, but the trajectory Discworld is following is very promising indeed.