I last watched the Alien Quadrilogy. It isn't necessary to see the last one. I like Whedon as much as the next nerd, but it isn't a good film. He botched basically everything. He was mostly faithful to the franchise, but damn, that doesn't make up for all the stupid stuff in the film. He littered it with quirky characters that don't seem to belong in space at all, no matter what century it is.