The only thing I can see that would be wrong with the neck is that that the trapezius seems to be attached under the skull. If you feel the back of your skull you will see that they attach farther up on the back side. Another thing to consider is that many characters that appear to have no neck are viewed from the front with the head haunched over. In your case, I would imagine he needs a little more neck. The trapeizius can only get so big at the top. Try to find a similar pose in a muscle magazine, to see what people of this build are like.
Your style is quite different from most others that post here. I feel that many are influenced quite heavily by the training materials that are common, such as VHS tapes. You seem to be influenced by no one, and it gives you your own style, which is a good thing.
From experience I have found that most people are subconsciously attracted or detracted by eyes. Even the monster in Beaty and the Beast, was able to be appealing because of his eyes. However, in your case, such "un human" colors, may cause people to subconsiously dislike him, which I don't think is your goal. Aliens characters can get away with drastic differences for eyes, but then they are aliens and such differences make them scarier. Anyway you might want to consider making his eyes more human in color. Imagine seeing a peson in public, with those colors for eyes. Would you not be freaked out, regardless of how attractive they may be othewise. Yet, E.T. was cute, and he didn't have anything else human like but his eyes (Yoda too). Alhthough, it is your character, so do as you feel is correct. Pulling it off might still work anyway, but be aware it may be a big design issue to work out. His eye brows are sort of 2D. You might try some other variations, to see if you can improve here.
In all, I think you are doing a great job. keep it up.
Urp
