Black swan

This photo is visually stunning. The bird contrasts well with the water, drawing the eye up the body and funneling it toward the red bill. Along with the beautiful subject, this photo takes our normal perspective of swans -- the traditional side view of a pure white bird -- and turns it literally on its head.
The symmetry of the piece is nearly flawless, except where the swan's head is turned slightly. However, if the head were completely in line with the body, the photo wouldn't be nearly as interesting.
I also love how the swan appears to be glaring at the viewer. Its feathers are wet and torn, and it seems to be saying "I'm sorry if I'm not in perfect condition." If the feathers were perfectly groomed, though, the photo on the whole would almost be too perfect.