I give it an A. It's not quite A+ material.
is like a spin-off of Alien
that just happens to take place earlier and only has one connection point. They have as much do with each other as DS9 has to do with VOY.
Like Ridley Scott said, Prometheus
actually is its own mythology and has a very good take on Ancient Astronauts. A sequel wouldn't have to have anything to do with Alien
are two of my favorite movies ever, so I'm probably more than a little biased.