I really like it except for the transition between the brain and the skull. It's a little too neat and tidy.
But nice work!
If I were being really nitpicky, I would say that the smaller veins shouldn't cross over the top of the larger ridges. Not sure how the skinning on that program works, but if you can layer the ridges over the veins so the veins disappear "underneath" the ridges, I think it might look better.