In This Island Earth, a scientist/jet pilot named Cal Meacham (the impossibly deep-voiced Rex Reason, which was his real name, apparently) orders some science parts out of a mysterious catalog, and follows the instructions -- which clearly did NOT come from Ikea -- to build a super-advanced wireless video telecom device that converses with an alien named Exeter. That Exeter is clearly an alien is utterly lost on Meacham and his assistant. So Exeter sends a magical, self-piloting plane to pick up Meacham and whisk him away to a secret science facility in Georgia that looks like an equestrian center/country club. Meacham falls in with Dr. Ruth Adams ("Dr. Ruth," hee-hee), an old girlfriend who pretends not to know him, and another scientist, Steve Carlson (Russell "The Professor from Gilligan's Island" Johnson). They finally figure out Exeter "ain't from these parts," and after The Professor makes one of the most odd and ill-fated filmic attempts to escape from an alien death-ray, Meacham and Dr. Ruth accompany Exeter to Metaluna. Exeter's home planet, Metaluna is constantly under attack by Zagons, who keep shooting radioactive meteors at the planet, threatening its existence.
This Island Earth is one of those movies held up as an exemplar of great 50s sci-fi, and it appears that it earned much of this reputation upon initial release back in 1955. The warm critical reception that welcomed it seems to owe a lot to the fact that it was 1) in color, and 2) had some special photographic effects. Both of these things were new at the time, and probably wowed the heck out of people seeing this stuff in a movie for only the first or second time. The movie made a big impression on kids like Steven Spielberg and other young sci-fi fans who would go on to reference This Island Earth in other films, documentaries, and books when they grew up.
The problem is, color and special effects aren't new anymore. And maybe you've had the experience of flat loving a film as a kid, only to revisit it later and think "You know, this actually kinda sucks." You'd rather have left alone the really good movie you remembered in your head, instead of burdening it with the actual, sorta crappy movie that exists out in the world where the rest of us live. I think we can pretty safely put This Island Earth in that bucket. The gaping, jaw-droppingly "wha?" plot turns and broken science may have paled in comparison to the awesomeness of the special effects in 1955, but not so much any more.
Objective Quality: 6/10
Bonuses: +1 for having one of the more iconic 50s sci-fi monsters; +1, the customary bump for an early appearance by Russell "The Professor from Gilligan's Island" Johnson.
Penalties: -1 for woefully under-utilizing that cool sci-fi monster; -1 for moving the characters around like cardboard cutouts, rather than even attempting to give them sensible motivations for their actions; -1 for making an utter mockery of science. I mean, by 1955 we must have known that shooting a planet with some meteors wouldn't turn it into a star, right? I mean, we must've know that.
Cult Value Coefficient: 5/10
[See explanation of our non-inflated scores here.]
Also of note, this interesting essay by Errol Morris about a strange echo from This Island Earth in Douglas Sirk's 1959 racial drama Imitation of Life with Lana Turner.