Just a little render that I did trying out the clouds (hence no terrain) I'm reasonably pleased with it, even though the water looks a bit like a snowy field :)
I like the rays you've achieved, but your clouds look a bit flat... could you try to increase their small-scale details a little?
I think the water is the best bit. It often does that if there is a light fluttery wind across the surface.
Andrew Randle
The Geostation
I think the water is the best feature too - the clouds look suspiciously flat. Are they 2D?