Very nice, pose, exposure, shooting angle. I always love the bejeweled look on the head when they surface from a dive.
I really do like the sense of habitat from the weeds. In a perfect world, perhaps the large one in front could be a bit further in front of the bird.
The bird seems to have a bit of a green cast on my monitor, which of course comes from reflection off the water. You might try removing that cast if it bothers you at all. Most noticeable on the breast of course, but even the back seems to have the subtle cast as well.