Well, technically flawless, there are only a few subjective constructive comments left ...
You could increase the disc diameter of the sun - double, triple it ... watch the reflections on the water afterwards and maybe increase the roughness to get softer, wider spread reflections.
Depending on the result, you may want to cut off the bottom 50-100px ... this is a matter of how dominant the sun and its reflection will be.
Cheers,
Volker