Because it's all shadows, it reads more like a hole into his head than an ear. At this size, you don't have the luxury of detailing the interior of the ear. Keep it simple.
Also, seconding increasing the contrast of the colours. The clothing could use some too, not just the skin.
You have outlines on the clothing, but not the head. Is there a reason for this? The outlines are also so faint that I think you might as well not have them anywhere.