some critique for you.(picture is at bottom for referance)

The subjects head corners are followed nicely by your model (blue area)(dont feel bad subject, everyone has head corners its nothing personal).

But, as you can see with the red area.

the subject has large sized neck muscles which buldge(1). this should be followed by your model to keep the head proportionate to the neck. the jaw line isnt really far off but you will know if it needs correcting after addressing the neck.

The model seems to be in a bust type format. it would be benificial to end either above or below the neck crease in order to get a good representation of your subject.(2) i prefer below the crease to show the full neck modelling(3).

The subject seems to have had a broken nose(could just be bad lighting) but if your using a mirrored sub D modeling technique, you should recess the nose bridge at the top a little then adjust side to side after the cage is no longer needed(4).

hope that helps you out. your model is showing good detail so far. keep us posted on it.