Hi John. Well done on getting close. We call them Goosanders over here, and I know how difficult it is to get close. I would lighten up the head and bill, especially the head. The black details on the back and tail look good.
Yes, these guys can be rather difficult to get close to! Although I almost always prefer a lower angle, I like the view of the top of the tail lying flat on the surface of the water, plus the submerged foot. Good small wake in front. Too bad the light did not bring out the neat deep green sheen these guys have at times.
Yes, this is a nice look at this oft skittish species. I agree with trying to squeeze a bit more detail out of the blacks. Exposure on this bird is difficult but you've done well here.