2001: A Space Odyssey is hailed as one of the greatest films ever made. While one can readily see certain aspects of it that are incredible, the film can also be readily dismissed as a self-indulgent confused mess. Since I find virtue in self-indulgence, I will choose to do the former.
The film is based on Arthur C. Clarke's novel, and is divided into four sections. On its own, each section is brilliantly done and each of the individual parts could be made into a movie of its own accord. However the sections do not come coherently together. Sure, it's possible to make a leap of imagination from one section to the next and connect it (and several people have, offering many different interpretations), but that doesn't mean it couldn't have been more coherent.
The first sequence is the dawn of man sequence, where we see the early African human (Australopithecines, surrounded by Joshua trees) trying to eke out a survival on berries and roots, and competing with other groups of humans for food and water. One group discovers a huge monolith, an object from outer space, but do not realise what to do with it. Soon after, however, they discover the use of a bone as a club (it took them that long?) and thus begins man's degradation. As the early hominid bludgeons his enemy to death and throws up his bone, it turns into a spaceship as we fast-forward several millenia.
This begins the second phase, the moon landing. Here we're introduced to humans on the moon who chance upon an amazing discovery: a huge monolith of obviously extra-terrestrial intelligent origin. As the moon crew investigate, a signal is sent off from the monolith in the direction of Jupiter.
The third phase of the films involves man's travel to Jupiter. The infamous HAL 9000, an artificially intelligent computer who becomes unstable, dominates the story and threatens the mission.
The final phase of the film is a bit too sugary for my tastes: Here, the one survivor of the mission to Jupiter lives his life out in a fantasy world created by those responsible for the monolith. Ultimately, he is reborn as a Star Child who returns to earth.
People have argued that the monolith is what enabled the early hominid cavemen to invent the club. My interpretation is that the monolith was useless to the cavemen during that evolutionary period. However, any civilisation that arose that developed the technology enabling them to travel to a nearby moon and uncover the object would certainly be within the reach of interplanetary travel. Therefore, the second time around, the monolith was buried beneath the moon's surface.
Kubrick is making socio-political commentary about at least four issues directly connected to the four phases of the film: that the inherent and violent nature of man is what leads to progress; the need to succeed pits man against one another; that there is danger in trusting machines to do everything a human does; and that there is hope for humanity after all (i.e., by becoming Nietzsche's Overman). As I mention above, these four issues don't necessarily merge in a coherent manner.
2001: A Space Odyssey pays painstaking attention to detail. There is no sound in the space. The dialogue is daringly minimalist. The re-use of previously composed classical music, Johann Strauss' Blue Danube waltz and Richard Strauss' Thus Spoke Zarathustra (cf. Nietzsche reference above), for the film score is a great master stroke. All of these features go to make 2001: A Space Odyssey one of the most thought-provoking films I've seen.