IAmSinistar: It's from that golden period of sci-fi in the 60s and 70s where the genre was maturing but the films were still treated like "normal" films, so they contained a lot of realism and human drama (e.g., Soylent Green, Rollerball, The Omega Man). This is one of them, and I feel it stands up very well. The antiquated technology makes it just seem even more ominous and probable, and the acting is refreshingly genuine.
I've seen several of those movies. In fact, Soylent Green is an old favorite. That's why I think it's strange that I've missed this one.