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.
I like this image as the barbed wire has a very interesting pattern on the outside of it and the repetition of the barbed wire looks really good. Also the way the barbed wire spirals down is very fascinating as it creates an illusion like effect.
I'm not sure what's going on in this photo as it looks like an optical illusion of some kind. Again, the placement, shadows and what look like reflections make this everyday object look like much more.