Hi Dan,
I think it looks pretty nice for an early work. Here are a few suggestions you might want to play around with:
1. Increase the haze quite a bit. Maybe around 10 or so would be good
2. Make the clouds seem heavier. This could be by increasing the density, or the edge sharpness, or even the depth
3. Possibly increase the camera exposure
3. Unchecking "blend by stone density" may help reduce or eliminate the problems you are having with the sharp edges and fanning on your fake stones.
4. Slightly darken the shoreline with another surface layer to make the waterline area seem wet.
Nice work with the image though, it has a good dreary mood to it.
-ryan