It should be studied in film class as a prime example of how to integrate design and story. Its emotional impact and meaning (substance) is so integrated with its unique aesthetic configuration (style) that one cannot really separate the two when analyzing it. The "science" aspect may or may not be bollocks, but it is presented in such a textured, believable way that is uncanny.
God, Ridley Scott used to be cool. The front-runner, in my mind, for both best horror AND best sci-fi film ever. Has its flaws and clichés, but they're totally overcome by the flawless direction, design, and ensemble acting. The alien might be the best monster ever designed for a film, and the use of color, light, and space contribute perhaps more than anything else to just how damn scary Alien actually is.
Ridlley Scott is a world-class master in the science of art and editing. Here he creates an atmosphere by fear and pace of an unseen and unknown evil. He sends us to a forbidden place for humans alone and adapts the most unpleasent creature for the crew which at some time knows it's expendable and the most important thing is bringing back alien life-form. But, it's not overall greatness.
8 - The retrofuturistic aesthetic Scott employed hasn't aged a day, though the same can't be said for some of the effects' finer details (the rubber facehugger being wiggled, the well-lit alien suit, the android head jump cut, etc...). Minor issues aside (and they most definitely are minor, in face of the film's astonishing organic props), this is still one of the scariest horror films ever made, and one of the best.
"I admire its purity." From the hieroglyphic credits to the strobe-lighty sweat-box ending ... still the most exquisitely designed movie of all time! H.R. Giger should have designed his own anti-amusement park. I wish Hollywood had given this guy more to do, but he did get to create the greatest of monsters! The sequels are all 6 flavors of "Suck!" (Well, part 3's sort of OK, I guess ...)