Jan,
Yes, I think that the shape of the hand is fine, it don't bother me that the shape of the fingers, in the shadow , is only suggested and not fully drawn. In that way you add to the light effect ( "you can't see what is in the shadow because the light is to bright, effect").
I did not notice your link to the reference at first, but felt that the ridge of the nose looks too wide, the shadow should be more to the right. After reading Stevens comments I found the link and got verification that the placement was off. Then, of cause
I began scrutinizing the whole thing.
I do not want to pick on you but think that you would want to know how it affects me. I feel insecure on how the shape is when the main key's to the understanding is not in the right place.
What I don't see won't confuse me, only what I do see!