This piece works with shadow art, which I find very interesting. I love pieces with crisp lines and the affect of the nails has exactly that. The contrast between the white wall, dark nails, and light shadows is dramatic, yet simple.
This pictures describes the term simplicity. Simplicity is where there is no busy backgrounds and the photo is simple. This picture is perfect for simplicity because there is a simple tree for the viewer to see with a simple background.