The first half is OK. I enjoyed exploring the colony, getting Newt's autopsy, Ripley getting laid etc. I loved how the dog chest-burst scene was juxtaposed with the funeral speech. I liked the criminals and how Ripley reacted to them. The one who boasts about raping and killing umpteen women, only to be told, "Then I must make you feel very frightened". There's a lot of good stuff in the first half.
It gets exponentially bad the closer it gets to the end.
Anyway, I prefer SF to Horror and don't want things "left to my imagination". I'd love to see what happened with the craft they found in the first film. It's probably easier to make a good prequel than a good sequel, partly because of what the later films did with the time line.