I think you did a good job balancing the exposure on the whites and darks. I face a similar challenge with loons, and soft light and fill flash are your friends to try and reduce the dynamic range in the image.
Neat pose, like his tail being up, they often have them flat on the water. The head looks a bit soft. You can improve the apparent sharpness by pushing the sharpening a bit more, esp. of the eye.
The crop is a smidge tight, but the pose helps make it work.
A fine looking individual. Nice relaxed pose, looks like it was preening perhaps? I like the dark mood to the image. Subject larger in the frame than I prefer, and although properly focussed the fine detail seems to be lacking...as if it was a large crop.
Thanks for the responses guys. I'll try another crop with more space. The current crop is large. This represents 10% of the full image so that maybe why you think it should be sharper. I'll try some additional sharpening too.
Current sharpening parameters in lightroom are:
Amount 66
Radius 1.2
Detail 25
Masking 26