The film was written by Howard Sackler, who later won the Tony and Pulitzer (in 1969) for his play The Great White Hope. And it stars Paul Mazursky, whom of course we all know from inventing hipster culture.
I saw it once on VHS (a terrible bootlegged copy) back in the late 1990s. I’ll be curious to revisit it. What I remember most of all is the strength of Kubrick’s cinematography (unsurprising, given his background as a photographer).
(It should be noted that Kubrick disowned the film, going so far as to block its release during his lifetime.)