Watching the stargate sequence after having read the book 2001, it's surprisingly comprehensible what's supposed to be going on.
Of course, the movie is really based on the short story "The Sentinel", but Clarke wrote the novel more or less in parallel with producing the movie, so it's neither exactly source text nor novelization.
Which makes it all the more weird that he stuck with putting the monolith on Saturn's moon Iapetus in the book.