|2001 is the kind of movie that reviews of it say more about the reviewer than it does the movie itself. Released in 1968, there are no digital special effects or the like-- everything is done with camera angles or special lenses or what have you. Amusingly enough, it's rated G-- since the ratings system was introduced that same year, the G rating didn't have the 'children-only' connotation that it does now. Its pacing is utterly unlike the vast majority of movies-- it's over 2 hours long, yet there's only 40 minutes of dialogue for the whole movie. And the soundtrack consists of exactly 2 songs: Also Sprach Zarathrusta (which nowadays people think of as the 2001 theme), and the Blue Danube Waltz.
One of the things that helped the realism aspect for me was that total unknowns were cast as the main roles; oppose this with 2010 which had several well-known actors. 2001's approach is better, because astronauts are generally unknown before they fly into space. Plus, there are no concessions made to how the public perceives space travel-- nothing like the *whoosh* the Enterprise makes in the Star Trek intro. This is not a movie made for the general public, this is art for its own sake. Granted it gets pretty incomprehensible at the end, especially after the acid warp trip from space to the bedroom, but there really wasn't any other way to portray that kind of scene, except by having the actor talk to himself, or through a narrator, and those would both have been too jarring given the entire rest of the movie.
In short, I believe you can't really call yourself a true science fiction movie fan unless you've seen this movie. I recommend it highly.