"2001" is one of those movies that you're either going to love or hate. I pity those who hate it, as its simply one of the best sci-fi films ever.
It starts off with "dawn of time," where humans were still primitive apes, who stumble across a mysterious monolith that aids their evolution to being human. Fast forward to 1999, another monolith is found buried on the moon and the origin is determined from Jupiter. The next evolutionary step is what "2001" focuses on: man and computer.
This movie's visuals are nearly poetic in nature. Kubrick's attention to detail is staggering. Keep in mind this was filmed before man landed on the moon in real life. In fact, conspiracy theorists to this day believe unused footage from this movie is what the US gov't used to "fake" the moon landing. Regardless of your own personal beliefs about that, it is a testament to how realistic and believable every aspect of this movie is.
Let me come back to my opening statement, that you'll either love or hate this. Though I clearly love it, I can see why some would not. For example, the first bit of dialogue is at 25:38, and up until then the camera and music tell the story. The last 23 minutes are the same way (there's about 88 min of dialogue-free footage total) and the visuals become the narrator. Those looking for fast camera cuts and laser guns and explosions and things of that nature will likely find this boring. The mood is relaxed, almost tranquil. The pace is slow. Take a deep breath and take everything on the screen in.
Something else that may be [unfortunately] seen as a negative is how open for interpretation the overall story is, especially the ending. Personally, I believe that's what makes it so great, but I do know some people like their plot spoon-fed to them.
"2001" was filmed in 70mm in the 2.2:1 aspect ratio, which means that though it was filmed over 40 years ago, the clarity and crispness of the picture makes it look like something that was filmed recently. For visuals alone, this is a Blu-ray worth owning just to show off your HDTV to friends.
This is one of those rare movies you "experience" more than you "watch."