The feet and hands are too small for the head. Feet are typically the same size as the head while hands are the size of the face. Also, the torso, while the right size for the head, is slightly too big for the rest of the 18 yr old body. Additionally, 8-9 heads tall is taller than average. Lastly, men typically do not have such defined waists. Their stomach usually comes almost straight up from the hip with a little widening at the chest area if they are well muscled.
On a more positive note, the break-down of the basic shapes is really good and the comparative proportions are interesting.
(side note on the stars: it was a tutorial; rating it on "Vision" and "Originality" and the rest did not really make sense)