Not bad at all!
Though there is a slight "end of the world" feeling to that mountain-line. Since you're working in the SE editor, you should experiment with "layered" mountains: Basically, extend the map further back and have several layers of mountains at uneven intervals, this way if you meld the fog and the mountains you'll get a receding horizon that gradually melds with the sky / fog, making it seem more natural.
Great stuff though ^^