The basic story is a familiar one: a spaceship from another planet crashes in the Arizona dessert. Everyone assumes it's a meteor except for school teacher and astrologer John Putnam who knows its a spaceship filled with aliens. Richard Carlson [Creature from the Black Lagoon, The Little Foxes] is perfect as Putnam. He gets every scene right, striking the perfect emotional tone with lots of energy and conviction. His femme fatale is Ellen Fields, played by Barbara Rush [When Worlds Collide, Peyton Place], who is equally as strong as her male counterpart. Naturally she's coiffed to perfection but is hardly a "helpless bimbo." Instead she is strong and self-assured and helps her man triumph in the end. The rest of the cast is great as well. Not a weak link in the bunch.
The script for It Came From Outer Space has its origins in a story by famous Sci-Fi writer Ray Bradbury. Harry Essex [Creature from the Black Lagoon] fashions it into a smart and solid screenplay. It's as good as Them! which is another one of my favorite 1950's Sci-Fi features. Director Jack Arnold [Creature from the Black Lagoon, The Incredible Shrinking Man] keeps the action moving at a good pace. He also wisely makes the human characters the focus of the film rather than the aliens. This is a good choice because the look of the space monsters is laugh out loud funny. But because it's such a good human drama the silly monsters actually make it all the more enjoyable.
I could go on but I think you get my point. If you're a fan of 1950's movies, don't miss this one. Great movie!
For more info check out the film's entry in IMDB.