I do not feel qualified to review this film, but I will anyway. I'll highlight the bad first: The star gate scene went on way too long, most of the movie is a test of endurance, and the humans which you are supposed to be scared for aren't emotionally reasonate.
That said, this is insane. It was made in 1968, and due to insanely good special effects and scientific accuracy, it feels like the concept of space today, not in 1968. A lot of people complain that they can't figure out the plot, well, think harder. Kubrick showed what happened and didn't have people spoon feed you info. You have to think about how it all fits together. Because of this, I think of this movie a lot, so when I am asked to recommend a film, I think of this first. Watch it four times over a week and think about it, and this will land among your favorite films too.