Earth vs. the Flying Saucers is one of the quintessential 50s sci-fi films, with stop-motion animation by Ray Harryhausen, lots of military stock footage, and a Cold War-zeitgeist plot about satellites. It was also the most prominent inspiration for Tim Burton's Mars Attacks!
I'm not sure the ins and outs of the plot are the most important aspects of the movie, but for what it's worth, Hugh Marlowe (who was also in The Day the Earth Stood Still) plays a scientist who begins seeing flying saucers, but can't prove it. Eventually, after the aliens blow up a Naval ship and all of the satellites the U.S. has launched into orbit, the aliens make contact with Marlowe, blow up a military base, and take a General prisoner to extract all of his knowledge about Earth. Ultimately, it's up to Marlowe to figure out how to stop these intergalactic oppressors.
The acting is pretty wooden and the plot kind of a mess, but what elevates this movie above so many others are the visual effects by Ray Harryhausen. The images of flying saucers crashing into the Washington Monument and Capital Dome are emblematic of the 50s sci-fi genre as a whole, and show up in every documentary I've seen about the era.
Objective Quality: 7/10
Bonuses: +1 for Harryhausen's stop-motion animation; +1 for its place in the 50s sci-fi canon
Penalties: -1 for Hugh Marlowe -- who apparently had the hairiest back ever -- taking a bathing-suit clad stroll into the sunset with Janet Taylor at the end.
[See explanation of our non-inflated scores here.]