I like it as it is, but 2 things pop into my mind while looking at it.
1) I would like to see it with a bit more contrast. Right now it looks just a little too grey for my liking. Just a bit, not much.
2) I can't say for sure, but maybe you could try cropping more of the left side off? As it is his elbow is already partially hidden. IMO, taking a bit more off would get rid of the feeling that we're missing something. This would also work because he's looking to the right, so he would be looking towards the extra space.