This is one of those movies that is so entirely exactly what it needs to be that it can't really be improved upon. You can iterate out the idea to great effect (ALIENS, countless knock-offs), but you can't take these pieces and create a superior experience. There are more ambitious movies, movies that do more for the human spirit, movies that find greater nuance in the human experience or mine deeper expressions of emotion and beauty. But there is no movie as good at being ALIEN as ALIEN.

This is the sort of movie that makes you okay with being alive for a while. (Also, there's a bit near the end that made me gasp so loud in the theater my girlfriend gave me A Look.)

Contains maybe the greatest ad-lib in the history of cinema.