The only things really off about the hair that I can see is the fact it has no gloss on it at all, and there’s no color variation along it’s length. It’s much too soft. Most hair has a gloss to it. If you’re using hair cards, plug the anistropic shader (not surei f it counts a shader, exactly? might be an input) in between the glossy and the cards, and rotate the mapping until you get what you like. For color variation on hair cards, you could possibly add a gradient or cloud texture, provided you warp it vertically well enough.
If you’re using strands, it should look anistropic by default when you add the glossy. You can add color variation with the is strand node and a color ramp. It even accepts transparency, so there won’t be any loss to your nice wispy tips.
The eyebrows could stand to be a bit denser. Unless the eyebrows are supposed to be sparse, you won’t see that much of the skin through them.
There’s still a huge gap between the eyeball and the eyelids, especially towards the nose on the upper area. If it’s giving you trouble, use a shrinkwrap on the eyelids (you can use a vertex group to specify strength if you don’t want it to match the eyeball shape exactly, the modifier respects weight paint).
The eyes need a catchlight, or they tend to look a bit dead. You wouldn’t have that problem here, if they were glossier, like they were wet. I’m aware this is a stylization, so you could probably comprimise by only adding gloss to the iris and pupil?
The lips could use some gloss, as well, for reasons of wetness, but this certainly isn’t a make-or-break.
The expression, now, could use some work. The lips are fine, but the eyebrows should be doing something other than resting neutral.