I've almost always been a book-before-film kind of guy, and I read 2001 years - even decades - before I saw it. I was already a Clarke fan when I found the book, and I've always liked the book far more than the film, which I found slow, near-dull, and on the pretentious side.
I expected to be quite pleased with this re-read of the book. While I liked the prose - it's still impressive how well Clarke is able draw the reader in with clear, intelligent exposition that's never boring - I found the story overall left me under-impressed.
For one thing, the parts don't really make sense together - the prehistorical prelude and TMA1 fit well, but then the HAL sequence feels like a whole different story. And the ending seems like yet a third. While there's a thread running through it all, the segments feel more like set pieces than a cohesive narrative.
Beyond that, the whole is less than the sum of its parts. This reads like the sketch of a novel rather than the novel itself. It says 'here are some interesting ideas and characters; there's a story here', but never gets around to fleshing things out.
This was quite a surprise to me. While I've always disregarded the movie, I had fond memories of the book. Now, it seems to me that it shows its origins as a film-novel hybrid. The film, which relied so heavily on imagery to hold things together, doesn't translate well to the page, despite Clarke's clear skill and attempt to bind it all together. Overall, I found the book disappointing on this go-round. I remember not liking the sequels as much, but perhaps, freed of the constraints of the film, they'll emerge as having better stood the test of time.