Hi Hammer

I think it needs some more work before going to ZBrush :p
As Jay said the edgeloops around the mouth are to much but also the edgeflow on the browridge needs some refinement

I would line your sourceimages up in maya and draw some refference curves so your model will have round edgeflows instead of harsh corners around the face also try to even out the size of your quads, by better distributing your edgeloops.
I like the way how you go around the ear btw it's a great way of avoiding triangles in that area.