I rewatched both Alien and Aliens for the upteenth time last week (I'm going through the rest of the Alien, Predator and AvP films to complete this monsterverse) and I'm still firmly in the Aliens side of the debate. Both are masterpieces and perhaps comparing them constantly does a disservice to both films, but I do feel like Aliens gets a bad rap as a shlocky action film. If Alien benefits from the character development, world building and emotion of the later films, then Aliens is hindered by the countless Gears of War-style space marine bug-hunting games and films that took the wrong message from the film. In Aliens, the marines are super cocky until they get their asses handed to them in the very first encounter where most of the unit is wiped out. Any catchphrase-spouting and "hurrah"-ing is done in parody. There's not even that much action in the film until the final 20 minutes.
Anyway, this isn't supposed to be about Aliens. There's not much to say about Alien as I don't think anyone frequenting these forums would disagree that this film should be preserved. I agree with pretty much all of the criticisms brought up on the pod, but, much like Chungking Express, sometimes things like conventional character development isn't always necessary to tell a compelling story. We know who these people are (truckers) and all that matters is they act believably, something Prometheus got so wrong.