The mouth and chin is supposed to be like wrinkled skin, you know how your fingers go when they've been in water too long? The effect was there in the first version but not so pronounced, plus the light wasn't hitting that part of the face very well so most of the chin area was in shadow.
I took the model back into Medium and built up a lot of detail, especially the chin and the sides of the head but pretty much all over. Then I redid the paintjob to highlight the forms better. Then I booted it back into blender and redid the lights so I had better coverage
Here's another render from front-on