HI, I'd make the trees about 1/4 - 1/5 of the size they are here and decrease the spacing between them. Maybe move the camera up to the rim of the crater as in the image Oshyan posted in your other thread (Obviously this is your choice and only my opinion). If you have gone with snow, I'd probably change it do dust (slightly light than the main rock) as you have no snow on the trees, so it looks a bit strange. Take the sun up a bit (maybe change the direction... behind you, left or right) and if you have a fast computer, I'd turn on soft shadows in the sun tab and raytrace shadows in the atmosphere tab. Render with some highish settings and see what happens. Let us know if any of this helps.
Cheers, Simon.