Mmm. You've got a couple of places there where you've got rogue singleton pixels that you could clean up (a couple kind of on a line with the left corner of the mouth where the dithering broke down a bit in different spots, and another two as a highlight in the hair that really need a third to connect them).
The line where the hair parts to show the ear may be too straight—ears and heads are curved, after all. And you're right on the edge of maybe having overdone the shading around the left eye and making it look . . . I don't know, like you could use a solid eight hours of sleep, maybe?
Other than that, once again, pretty good.