It is an unimaginative, unambitious movie made for teenagers. As disappointing as the third and fourth Alien films are, both were imaginative, ambitious, and made for adults.
It doesn't help that Paul W.S. Anderson is a terrible filmmaker who can't even execute a cheap jump scare, let alone build dread or tension. The AvP video games are hardly high art, but they were at least successful in establishing and maintaining the proper mood.