Wow, this looks excellent. I think you did really well on the faces, especially Fiona's expression. Is this after you made the changes?

My only critique is that at first I thought Sha was holding something white in his hand, like a rock or something, instead of it just being Fiona's shirt there. When I look at the full-size image, it looks like the shadow under his hand gets a little bit lighter towards his fingers, and it keeps coming across as reflected light and making the negative space look 3Dish. Hope that makes sense.