It's a great movie, but it falls completely flat on its face during the ending. They honestly need to find people who read the comics cause they would have written a better ending than that.
It started strong, though personally I think the audio in the beginning could have been better. The sound of the environment was louder than the actors talking. I wasn't completely sure what they were saying until they go meet the rest of the cast in a quieter area.
As the movie goes it gets all the points for a good Alien movie. Though the movie didn't seem to want to use the Alien to actually stalk and hunt them in a better way than just making sound and being there as scare factor for the group.
The ending should have been that the aliens crashed to the planet and a whole infestation happened. That could have led to a nice sequel bringing in the Marines to fight back and try to save Weyland company. But we got... That.