neckmuscles look kinda strange, ending in his jaw like that. maybe an adamsapple? He seems to have low bodyfat so Sideabs, ribcage, arm muscles need more definement. try moving his biceps towards his triceps and vice versa
slowly moving toward a model i've wanted to make for a while now...
The chest and back of the shoulders look strange.. I'd bring the pecs closer together and remove that weird crease above the shoulderblades, but that's just me. The collarbone also seems to jut out a bit too much.
You seem to wish to make him slightly muscular, but the effect is skewed because your serratus muscles look like his ribs are sticking out instead. And I agree with Jose with the crease on the shoulderblades, although the chest looks fine to me. Also, the ears seem a bit sharp, but that is probably intentional...
Could I request pics of just the arm in the first pic? I wish to study the polyflow for my Ninja Turtle model.
The ears are a bit pointy, like the elves in LotR.