There are a lot of things I don't really enjoy about this film, but damn it's hard to ignore the good stuff. Alien is the pinultimate sci-fi horror film, only matched by maybe The Thing. You've got well-written characters (especially Ripley), eerie and atmospheric environments, and well-done visuals that draw you into this world and can also be pretty freaky. There are a few things about Alien that I have gripes with, such as the sometimes-overdone acting. The horror/action parts of the film, mostly at the end, can also drag on for a while without anything really happening. This slow nature of the film works well for the first half, but once the ship turns into a shadowy mess in the background its hard for me to stay engaged. I do think that the sequel to this film is better than the original, but there are few films that can match Alien in terms of sci-fi horror.