Let's take a look at the first screencap from Prometheus below.
All of the screenshots just don't show their clarity when viewed at a reduced size, so I recommend viewing the full-res versions and judge for yourself. Seeing the face of an Engineer for the time on the screen looked amazing. The
I have to say this, but Shaw (Noomi Rapace) just has a rather unique face which might look odd at certain angles. This particular screenshot doesn't look that great, but is much better at normal viewing speed. This has to do with the lighting and some possibly overdone makeup due to Noomi's very fair skin.
Charlize Theron's character had different opportunities for more lighting situations, in addition to having lighter hair, and her skin color was more versatile. I could go on for pages with an "in-depth" review, but suffice it to say, Theron looks great in this film.
At this particular part in the movie, I was impressed with the sharpness and clarity, while still maintaining a low-light atmosphere.
A good example of viewing the full-res size, is comparing it to the one below. There is much more detail in the larger screenshot, and especially when viewing this scene at normal speed (i.e., 23.976 fps) instead of a screengrab.
The Prometheus: 4-Disc Collector's Edition looked fabulous on Blu-ray. Screenshots came out rather crisp, which means the movie is only better.