Clarke wrote this novel around the same time he co-wrote (with Kubrick) the screenplay for the movie of the same name. While the movie is very long, slow, and difficult to follow (and, IMO, awesome!) the book is quite short and much more accessible.
2001 is about the quest to discover how a mysterious structure came to be buried under the surface of the moon 4 million years before humans first ventured into space. Even more shocking than the answer to this enigma is what happens to the astronaut who journeys to Saturn to solve it.
This novel is pretty much the epitome of classic science fiction, and Clarke infuses such wonder and suspense into his story that I can't help picturing him writing it on the edge of his seat. While the dialog is sparse, and the pondering about human evolution and technological advancement often takes over, the story is full of mind-blowing turns that are fun to discover.