Stanley Kubrick's 2001: A Space Odyssey is a classic of cinema, universally revered by film buffs as one of those experiences you simply have to see. On the big screen if possible. But on its 1968 release, 50 years ago today, not everyone agreed. Dealing with abstract concepts, and delivered with audacious scale, five decades ago it was a radical and challenging prospect. 'Somewhere between hypnotic and immensely boring' While some critics failed to see the artistic worth in Kubrick's film when it was originally released, it didn't help that they were not even shown the same film in many cases. Full Metal Jacket at 30: Matthew Modine on working with Stanley Kubrick – and the ‘toxic’ London set Some critics saw the original 161-minute cut shown at premieres in major US cities like Washington D.C., New York, and LA, while others saw the shorter, general release version that was in theatres from April of 1968. Renata Adler, writing in the New York Times, said the film was "so completely absorbed in its own problems - its use of colour and space, its fanatical devotion to science-fiction detail - that it's somewhere between hypnotic and immensely boring." "The uncompromising slowness of the movie makes it hard to sit through without talking - and people on all sides when I saw it were talking almost throughout the film. Very annoying." Extra scripts required? (Photo: Metro-Goldwyn-Mayer) The film's open-to-interpretation approach to narrative - poured over by film and pop culture academics for decades since - was slightly lost on Adler, who said: "Three unreconciled plot lines - the slabs, Dullea's aging, the period bedroom - are simply left there. "Some extra scripts seem required." Many critics realised that, while what they were watching was certainly visually spectacular and encapsulated ambitious themes, to the average movie-goer, 2001 was not going to be a smash-hit. "A small sphere of intellectuals will feel that Kubrick has said something, simply because one expected him to say something," wrote Kathleen Carroll in her 1968 review for the New York Daily News. "Most moviegoers will only wish that Mr. Kubrick would come back down to earth." 'A shaggy God story' John Simon, writing in politics and culture magazine The New Leader, offered his less-than-favourable take on the film, while arguably stumbling upon one of the film's central messages. "This film is fascinating when it concentrates on apes or machines," he said, "and dreadful when it deals with the in-betweens: humans. "For all its lively visual and mechanical spectacle, this is a kind of space-Spartacus and, more pretentious still, a shaggy God story." 'Despite the size of the starry firmament, the idea of space travel gives me claustrophobia' (Photo: Metro-Goldwyn-Mayer) Stanley Kaufmann's review for The New Republic seemed to be focused on his own dislike of the concept of space travel; again, the feelings the film brought up for him were arguably intended by Kubrick in the first place. "His [Kubrick's] film has one special effect which certainly he did not intend. He has clarified for me why I dislike the idea of space exploration. "The interior of Kubrick’s spaceship is not greatly different from that of a jetliner, but at least planes go from one human environment to another. No argument that I have read for the existence of life elsewhere has maintained that other planets would be suitable for men. "That is why, despite the size of the starry firmament, the idea of space travel gives me claustrophobia." 'The monkey stuff is OK' Kubrick's classic currently holds a 96% critical approval rating on Rotten Tomatoes, meaning that in modern times there are only 4% of reviewers with whom the film did not sit well. Perhaps that's something to do with how the film has aged. 'The monkey stuff is okay... if you like seeing people in hair suits jump around going 'uck-uck''(Photo: Metro-Goldwyn-Mayer) Stephen Hunter, in his Washington Post review written in "the actual 2001", called the film "pretentious, abysmally slow, amateurishly acted and, above all, wrong. "An annoyance wrapped inside of an enigma as constructed by a cosmic ego that had been praised so much he believed it. The monkey stuff is okay... if you like seeing people in hair suits jump around going 'uck-uck.'" Though he did add one caveat: "Maybe it's just that I wasn't high this time when I watched it." The Shining: the horror masterpiece the critics loved to hate Kubrick's response: 'Slambang pans' It's unlikely that Kubrick himself would have been worried by any negative responses to 2001: A Space Odyssey. Speaking to the New York Times in 1976, the director offered a description of the reviewing process which revealed his disdain for critics. "The reviews that distinguish most critics, unfortunately, are those slambang pans which are easy to write and fun to write and absolutely useless," he said. "To see a film once and write a review is an absurdity... There's not much in a critic showing off how clever he is at writing silly, supercilious gags about something he hates." • Have your say on the latest TV and film with Screen Babble, our discussion group on Facebook This article originally appeared on our sister site, iNews.