It's very well done. He is a good artist.
However, he should have rather used a more appropriate tool for the job. A touch sensitive stylus with a sharp point gives you more natural brush strokes with more detail in them and they don't obscure the area you're trying to draw in. Like with a Wacom Cintiq attached to a PC or Mac or a Samsung Galaxy Note tablet or phone (they use Wacom sensors and stylii and shock, horror: Android).
