There are two things that make Black Christmas different from any number of eighties slasher films: 1) it invented the style they used, and 2) it's smarter than most of them. For instance, the woman who does "run up the stairs instead of out the front door" may indeed be exhibiting an unconscious desire to climb the ladder out of the gene pool, but at least she has a reason for doing it--she wants to help her friends. Simple as that. And she arms herself first. Part of the reason Black Christmas works is because it, like Halloween after it, at least partially succeeds in developing its characters (Jamie Lee Curtis's Laurie Strode is, I'd warrant, not too far removed from Olivia Hussey's Jess). Black Christmas is also surprisingly light on gore, choosing instead to build suspense through frightening imagery and sounds. Director Bob Clark, learning from his mistakes in Children Shouldn't Play with Dead Things, keeps his shots tight and his pacing smooth. All of this leads to a finale that, like the movie itself, isn't entirely satisfying, but is pretty creepy.