Since this is a review of the sequel to "Alien", it will contain references to the events that took place in the earlier film. It does not contain any major spoilers for "Aliens", though. More after the jump:
Making a follow-up to a film as terrific and scary as Ridley Scott's "Alien" is, at first glance, ill-advised. I can name maybe a dozen good sequels in film history, and none in the sci-fi or horror genre (with the exception of the "Star Wars" franchise). "Alien" is a masterpiece. Couldn't it have been left as is? In this case, the answer is no. "Aliens" is an equally masterful work, for one reason above all else: it doesn't try to duplicate what made the first movie so successful.
It's been 57 years since Ellen Ripley (Sigourney Weaver) put herself into hyper-sleep after watching a vicious alien destroy the rest of her crew. She's picked up by a ship, and the next half-hour or so is devoted to explaining the events that brought her here. Exposition in films often feels too much like the character is talking to the audience, a pitfall "Aliens" avoids by having Ripley explain things to a board of corporation members as well as to us. They initially greet her story with skepticism and jeers, but after receiving no word from the colony currently stationed on the plant they ask her to go on a mission with a group of marines (ostensibly to wipe out the alien population once and for all). After some initial doubts, she agrees.
I stated earlier that the film doesn't try to duplicate "Alien". That's true for the most part. But early on that's not the case, as the initial investigating scenes are very similar in tone and style to Scott's masterful first half build-up in the earlier feature. Here they obviously don't work quite as well: since we know what the aliens are and what awaits these characters, much of the creepiness is gone. But they're still moderately effective, thanks mostly to Weaver's terrific (and mostly silent) portrayal of Ripley's terror for both herself and for the people now with her.
However, even here the film is careful to begin distancing itself from predecessor. That begins with the characters surrounding Ripley. In "Alien" they were basically clueless: pawns in their company's extremely stupid attempts to capture the creature. Here they're well aware of the danger they face, but they foolishly think they can wipe out the aliens just like that. Indeed, there's a certain amount of dark humor in watching the marines' bravado, knowing that they've grossly underestimated what they're going up against.
There's also a new character: a young girl named Newt, who has survived the massacre of her people. Ripley takes a liking to this courageous young girl, and promises to protect her. Of course, that's easier said than done once the aliens begin to attack.
And attack they do. This is a spoiler-free review, but let's just say that the final 90 minutes are basically one long (and extremely impressive) action scene. After the initial attempts at building tension, it's as if director James Cameron decided to just forget suspense and go straight for visceral thrills: moving from one stunning action set-piece to another at a stunningly fast pace. And that is the major difference I was referring to. "Alien" is truly scary, whereas "Aliens" is merely a non-stop thrill ride. Which film you prefer* depends on your personal tastes when it comes to pacing, but both are masterful at what they do.
* I admit to liking "Aliens" slightly more, which is odd since I'm usually a fan of atmosphere over high-octane action. But again, both are great.