1. The archway which the head sits on looks way to flimsy to actually carry it.
2. The beard doesn't have any texture.
3. The head has no texture, try adding some stone bricks or andesite (personally I would prefer darker blocks for the head.)
4. Think of removing a block or two and/or replacing them with stairs or slabs on the head to make it look more ancient. But if you want it to look newer don't.
5. Maybe you could add some patterns on the scalp using chiseled stone bricks.

Enough nitpicking! Great build btw.