He's smiling. He sees something he likes. He's thinking something. I wonder what it is.
Stylistic aside: I realize, of late, I've got the drawings of Tom Bachtell on the brain, the fellow who does those wonderful little portraits for the "Talk of the Town" section of the New Yorker. (That link points to a great little video of him at work.) He has an amazing capacity for capturing a person's likeness in a few dashed strokes — he's a masterful caricaturist in best possible sense of that word — which I wouldn't even attempt to emulate. (I'll stick to doodling the fictional folks that bubble up in my brain.) But I do love the looseness of his lines and his rough brushy textures. Good stuff.