I think the performances / direction and effects are all good. It's well shot and the suspense is high throughout. Unfortunately, the plot is weak and full of holes. Jumping from barely believable happenstance to implausible leaps. It pretty much rehashes most of the previous franchise, which peaked at the second movie.
The promised explanations for the Prometheus chains are weak, and if you just want to know what's going on, this isn't really going to help. The whole experience was for me unsatisfactory, and as much I want answers, i'm not sure if they get around to making any more i will sit through it...