Sunlight on Mars is, if I remember correctly, 43% as bright as sunlight on Earth... but that's 43% as bright as the brightest sunlight on Earth, without cloud cover or atmospheric hazing, which is pretty darned bright. Where I live now (in Portland, OR), there is probably much less light than there would be on Mars, things look just fine here.

The eye does percieve color tonality different in low light, however, and there's not much that the brain can do to compensate for this. To the human eye, Mars would appear a bit more silvery-blue than it does in photographs (since the blue receptors in the eye are more light-sensitive than the red or the green receptors) -- a light roughly between sunlight and moonlight. I think this would actually be a rather pleasing effect, but it's not what is shown in these renderings.

Cheers,

Nathan.

P.S.: For a startling example of the way our eyes transform color, try taking a long-duration exposure of a landscape lit by the full moon. You'll find that the resulting photograph looks perfectly daylit! This is because the color of moonlight is exactly the same as the color of sunlight -- it's just sunlight bounced off a neutral gray reflector -- but our eyes are unable to see this due to its dimness.