Think it looks great.
I can't work out whether the guy's shirt is meant to then fade into the background, or the background is meant to be separate. Can you please clear this up for me?
I like his teeth, and especially the attention to wrinkles and creases. Well done.
I think you could have maybe put more detail, ie. shading into the eyebrows and hair but it may well have ruined the simplistic feel of the piece.