sup pretzel, good stuff, when it comes to the lineart i feel like you nailed it on the sketch fase, but on the final piece the ticker lines on the body takes the attention away from the face, also it looks more appealing when the lines vary in thickness just like you did on the sketch.
On another note, i did some observations on the second studie that you're doing, i hope you don't mind
all in all, good stuff i say