Saturn being at 10 A.U. means sunlight on Titan's cloud tops is about 1/100 that on Earth's. That's 4000 times the illumination of Earth's moon. Titan's atmosphere is described as opaque smog. If it were 99.97% opaque the surface would still be illuminated like a full moon. Photos from Huygens seem to show some light gets through.
Would a (warmly-insulated) astronaut see pitch black? A diffusely glowing brown sky? A foggy city streetlamp? I'm finding it hard to picture.