I like the pose, but my suggestion would be to have the subject wear a color other than black. It seems so much detail is lost it's almost like he's a floating head.
I think this would be a stronger portrait without the sunglasses. You also lose quite a bit of the subjects shape in the blackness, would have liked it it you still had some definition around his shirt
I wish there was a bit of separation between the background and Bob's shirt. Right now his body seems to just disappear leaving his head and limbs a bit disjointed.