I’ve seen it a few times through, and I don’t think the novel is strictly necessary (also, it followed the movie IIRC.)
Pacing feels glacial compared to modern tentpole films, but it’s best seen in a large format for sure. The effects are so well-done that you forget it’s from 1968. Even the trippy end scenes – purposefully disorienting IMHO.
Watch it, when you’re in the mood for a slow, visual, thinky movie. Nobody on-screen figures things out for the audience. Followup with 2010 if you want to understand what you just watched, though. 
