My young child has an uncanny ability to sit through the first half. Yes the movie is slow, but it is hypnotic when you drop all expectations and all conditioning on what a narrative should be. I talk him through and describe what is happening on-screen and it's helping me understand the themes and symbolism a lot better too. This feels the most likely a pure "moving picture" and you get to take in all the inventive and convincing designs with some relaxing (and sometimes not-so-relaxing) music.
The sequel (2010) is pretty good, but the main problem with it is that it spells out everything that Kubrick left ambiguous, shines a light on all the big mysteries. So it's satisfying in the sense that you get to know concretely "oh, that's what it was then", but in doing so it also becomes like any other story and thus there is little special about it. It's still a good movie with a terrific cast (talking about 2010), but 2001 while not for everyone, is undoubtedly unique and unlike anything else. It's a purely cinematic experience and that's what Kubrick excelled at.
