Nice job, except the only major thing I see wrong with this head is that the ears are too low. If you trace your finger from your nose to your ear, you should end up plugging your ear with your finger. I think the problem you had was lining up your reference photos for both side and front. Also, maybe it was just this particular person in your reference, but your ear is rotated a bit. Not sure about this though. It just looks off.
EDIT: Looks like someone commented about the ear rotation already. Can we see your reference? I mean I know things differentiate person to person, but I'm having a hard time imaging someone's ear actually being that rotated and that low on the skull. What ever floats your boat, but that's the critique I'm giving it.
Yours:
Reference:
"If I have seen a little further it is by standing on the shoulders of Giants" - Isaac Newton
-Computer Animation Major @Baker.edu-