To say it bluntly; the clouds are awful (you know I mean this positively). I think if you just add some default clouds you'd be better of. Or scour the forum for some nicer clouds.
The rocky beach is strange indeed, postwork? Some merged rocks (highest raise) of different sizes would work good here, blended by distribution shader to cover only shore.
The trees don't mix well; some seem to have huge leaves in comparison to others. Perhaps some other species would be nicer, although I do like the reddish ones.
I hope this critique is any good to you, as it sure has potential.