You're doing really well to vexel a really crummy picture.
A couple of things I noticed that might make it look better: The shadow that defines his chin, in the photo it's very large and dark on the right side but not on the left, whereas you actual taper it and then let it expand again into the left side. Also, his eyelashes are more straight-across in your vexel than they are in the photo.
Notice on the right side of the nose where there's more shadow in the 'crease' around the top of the nostril? Also on the outside... I think emphasizing those shadows a bit more will perk up the vexel.
A tip on getting tips : P Tell us what program and tool you're using. Then people who use those specifics are more apt to help you and be helpful to you.
Wow that's a hard picture to vexel huh D:
There's something going on with her chin.. it's big in the original but it's huuge in your vexel like it is stretched or something.