I am posting a shot made in a studio setting using three lights. The photos are in 100 ISO and in RAW. You can see the scheme of the lights here. The key light has eight angled soft box, 45 degrees above the face of the model. The Fill light is set up with a half f-stop less than the key light. I have back light high above the back part of the hair and one more flashlight for the background. You can see a soft light upon the face, slight back light on the hair, so that the haircut and the color of the hair are emphasized. The roots of the hair in this case are darker when compared with the ends of the hair. The purpose of that is to highlight the haircut as well as the color diversity.
The lens 24-105L works very well on 75-105 mm. The aberrations are not seen, just the vignettation in the angles due to the matrix. The image in the center is sharp and has very good color rage, due to the good lens. At the ends of the photo the image is not so sharp due to the slightly aberration of the zooming. The gradation of the colors is very soft; one can notice the L quality of the series.
If you look more carefully at the hair you may notice that the black color lacks the color range one would find in a movie. The reason is simply that the digital technology lacks enough dynamics. I look forward with great anticipation to the successor of 5d primarily for the improved dynamics of the image.