I find the jawline a bit distracting. In the original 2-color version, the equally spaced pixels convey the idea of a continuous line that is thinner than 1 full pixel. Now if you add one color that is an intermediate, you have the ability to represent the thinner lines using continuous pixels of this color.
Here for example, this shows a "jaw"line that starts thin, becomes thicker (full white), thinner again, and fades as unattached pixels.