The film earned $8.5 million in theatrical gross rental from roadshow engagements throughout 1968, contributing to North American rentals of $15 million during its original release. Reissues have brought its cumulative exhibition gross to $56.9 million in North America, and over $190 million worldwide.
Upon release, 2001 polarized critical opinion, receiving both ecstatic praise and vehement derision. Some critics viewed the original 161-minute cut shown at premieres in Washington D.C., New York, and Los Angeles, while others saw the nineteen-minute-shorter general release version that was in theatres from April 10, 1968 onwards.
In The New Yorker, Penelope Gilliatt said it was "some kind of great film, and an unforgettable endeavor ... The film is hypnotically entertaining, and it is funny without once being gaggy, but it is also rather harrowing." Charles Champlin of the Los Angeles Times opined that it was "the picture that science fiction fans of every age and in every corner of the world have prayed (sometimes forlornly) that the industry might some day give them. It is an ultimate statement of the science fiction film, an awesome realization of the spatial future ... it is a milestone, a landmark for a spacemark, in the art of film." Louise Sweeney of The Christian Science Monitor felt that 2001 was "a brilliant intergalactic satire on modern technology. It's also a dazzling 160-minute tour on the Kubrick filmship through the universe out there beyond our earth." Philip French wrote that the film was "perhaps the first multi-million-dollar supercolossal movie since D.W. Griffith's Intolerance fifty years ago which can be regarded as the work of one man ...Space Odyssey is important as the high-water mark of science-fiction movie making, or at least of the genre's futuristic branch." The Boston Globe's review indicated that it was "the world's most extraordinary film. Nothing like it has ever been shown in Boston before or, for that matter, anywhere ... The film is as exciting as the discovery of a new dimension in life." Roger Ebert gave the film four stars in his original review, believing the film "succeeds magnificently on a cosmic scale." He later put it on his Top 10 list for Sight & Sound. Time provided at least seven different mini-reviews of the film in various issues in 1968, each one slightly more positive than the preceding one; in the final review dated December 27, 1968, the magazine called 2001 "an epic film about the history and future of mankind, brilliantly directed by Stanley Kubrick. The special effects are mindblowing." Director Martin Scorsese has also listed it as one of his favourite films of all time. Critic David Denby later compared Kubrick to the monolith from 2001: A Space Odyssey, calling him "a force of supernatural intelligence, appearing at great intervals amid high-pitched shrieks, who gives the world a violent kick up the next rung of the evolutionary ladder".
Pauline Kael said it was "a monumentally unimaginative movie", and Stanley Kauffmann of The New Republic called it "a film that is so dull, it even dulls our interest in the technical ingenuity for the sake of which Kubrick has allowed it to become dull." Renata Adler of The New York Times wrote that it was "somewhere between hypnotic and immensely boring." Variety's 'Robe' believed the film was a "[b]ig, beautiful, but plodding sci-fi epic ... A major achievement in cinematography and special effects, 2001 lacks dramatic appeal to a large degree and only conveys suspense after the halfway mark." Andrew Sarris called it "one of the grimmest films I have ever seen in my life ...2001 is a disaster because it is much too abstract to make its abstract points." (Sarris reversed his opinion upon a second viewing of the film, and declared, "2001 is indeed a major work by a major artist.") John Simon felt it was "a regrettable failure, although not a total one. This film is fascinating when it concentrates on apes or machines ... and dreadful when it deals with the in-betweens: humans ...2001, for all its lively visual and mechanical spectacle, is a kind of space-Spartacus and, more pretentious still, a shaggy God story." Eminent historian Arthur M. Schlesinger, Jr. deemed the film "morally pretentious, intellectually obscure and inordinately long ... a film out of control". The BBC said that its slow pacing often alienates modern audiences more than it did upon its initial release.
Science fiction writers
Science fiction writers had a range of reactions to the film. Ray Bradbury praised the film's photography, but disliked the banality of most of the dialogue, and believed that the audience does not care when Poole dies. Both he and Lester del Rey were put off by the film's feeling of sterility and blandness in all the human encounters amidst all the technological wonders, while both praised the pictorial element of the film. Del Rey was especially harsh, describing the film as dull, confusing, and boring, predicting "[i]t will probably be a box-office disaster, too, and thus set major science-fiction movie making back another ten years." However, the film was praised by science-fiction novelist Samuel R. Delany who was impressed by how the film undercuts the audience's normal sense of space and orientation in several ways. Like Bradbury, Delany picked up on the banality of the dialogue (in Delany's phrasing the characters are saying nothing meaningful), but Delany regards this as a dramatic strength, a prelude to the rebirth at the conclusion of the film. Without analyzing the film in detail, Isaac Asimov spoke well of Space Odyssey in his autobiography, and other essays. The film won the Hugo Award for best dramatic presentation, an award heavily voted on by science fiction fans and published science-fiction writers. James P. Hogan liked the film but complained about the ending that didn't make any sense to him, leading to a bet about whether he could write something better or not; "I stole Arthur's plot idea shamelessly and produced Inherit the Stars."