First of all. Should Cameron Diaz ever be allowed to act again? To call that a bad performance would be an insult to bad performances. That was a historically horrific performance. Any small chance that Diaz had at being a serious actress is now completely done after that. Laughably horrible.
Two, the movie was extremely boring, and not very thought provoking at all. I can sit around and ponder human nature without having to watch terrible actors, play out a terrible story.
Third, there was not a single likable character, and even worse, it seemed like that was done by design. You were not supposed to like, or feel sympathy for any character. It was quite effective. I wanted them all to just die to be honest. Aliens included. Kid included. Everyone was just one big mope in this movie. Everyone literally just moped around, and they called it a movie. You could barely distinguish the zombie "employees," with regular people, because they all seemed like zombies.
Lastly, nothing really makes sense. From the characters reactions and emotions, to the literal story line, it all just seems random. This is just a really bad movie, disguised and couched as a "thinking mans movie," which is meant to be confusing. Give me a break. A bad movie is a bad movie. And this movie was bad.