The 50s was Hollywood's probably worst-ever decade, the highlights of that period very ironically being mostly low-budget, so-bad-they're-good sci-fi and monster movies. Even though SOF isn't by any means a brilliant exception to the rule, it does offer something that a number of 50s big-studio movies did have: beautiful women (in this case one woman) and great Technicolor visuals. Susan Hayward has never looked better: she is quite simply stunning. The coastal night scenes are visually impeccable. The story isn't too cheesy for that period and refreshingly presents communists as the bad guys. (The movie was made post-McCarthy-clean-up so there was a pleasant hiatus that lasted several years regarding left-wing propaganda films that glorified communists or at least tried to soften the brutality of such regimes.) Clark Gable, if a little old, in the lead role can't hurt either.
Compare 40s/50s beauties like Liz Taylor, Olivia de Havilland, and Susan Hayward to modern-day wrecks like Julia Roberts, Jennifer Aniston and Cameron Diaz. Sad...