So I must admit that my expectations for this movie were very different from what actually was put on film. Somehow the previews has me convinced this was epic space opera and not a prequel to Alien.
Still, it does not really work in that context either. This is a movie that wants to be serious sci-fi but the cast of characters is even less developed than in the Alien tetralogy. They are all prop pieces to be killed or die heroically and always stupidly.
The main character I guess is motivated by faith; she wears a cross after all. Noomi Rapace has neither the face nor the acting chops to pull of a similar role to Ripley. Charlize Theron is I guess supposed to be evil and there is some subplot with her father, but it really does not matter. The only other character of note is the android who despite the constant imprecations about his ability to feel emotion is probably the most interesting character. Sadly, Scott has him doing all sorts of inexplicable things during the movie that blunt his efficacy.
Then again they all do stupid things over and over. I could make a list, but that is probably one of the more enjoyable moments in the movie so I wont spoil them.
The real flaw is how the movie opens with the biggest plot twist. The rest of the movie reveals almost nothing of import and since the main character is so wooden the ending makes no sense. The entire thing ends up being like another Alien entry except without the iconic villain and a credible protagonist.