This painting is a study in intensity. This concept was a little confusing to me at first. I'm used to playing lights against darks (value changes) to show dimension or a focal point. In this painting, I used a similar value throughout, not worrying about going from light to dark. I made the area near his forehead and down near his shoulder more intense to guide your eye around the painting. I liked this exercise because, first of all, it was difficult for me. That's a good thing, you always need a little challenge in your painting. Second of all, it gives me another tool for expression in my painting. I don't always need to show an object is dimensional, nor do I need to contrast light next to dark to get someone's attention.
The Impressionists sometimes disgarded value and instead used a similar intensity throughout their paintings (think of Monet's Waterlilies.) When they wanted to draw your attention to something in the painting they changed the intensity.