What impresses me the most is how he used the project as an excuse to experiment. He’s a kick-ass cartoonist in what I’d guess is his “default” style, but has been incorporating photographs, collage, silhouettes, and screen-printing effects. He can do the Schoolhouse Rock thing. He can mimic Edward Gorey and Ernie Bushmiller and Mike Mignola (and do a much better job of it than he gives himself credit for in the descriptions).
And this one is my favorite, just for the expressions.