Overall the shot is okay. I think it needs more contrast in the background. I don't personally feel "peace of mind" when I see this as much as I see "contiplation".
Usually not good when a background element has a line that goes through the subject's face. Colour balance looks a tad off. Bridge isn't sharp, needs a little more dof. Composition doesn't quite feel balanced.
He does look peaceful. Seems to be a little bit of over-saturation here, and there are odd burn marks in the sky.. overall, while it's a great composition, the colors, contrast, saturation, and other elements, don't add up.