I say just redo the entire back leg and put some detail into it so that it can compete with the front leg to some extent.
The back arm isn't entirely black, so why should the leg be?
For a suggestion, i would make the back leg come way forward so like the foot is below the elbow or something
those neck muscles are crazy on his skull, lol..
Some reason im liking the waiste area and thigh.
edit: also when you raise an arm, your shoulder usually raises as well.