What I like about the style is that it seems to be subtle and realistic--just a monk walking through the rain. This is exemplified by the limited palette and shading scheme; the familiar ochre-orange outfit and unusual but complimentary skin tone makes the figure the first thing we notice. But on second look we see the reflection and a surreal aspect suddenly enters the picture when we find a hidden city.
He's also done silkscreen (t-shirt) designs for Death Cab for Cutie, which you can see on his website. Here's another image by him, which I like a lot; the wobbly lines, sketchiness, color-outside-the-lines style adds to the spontaneous nature of the busy city scene:
