Very dramatic. :-) I'm a Bryce amateur and have no Terragen experience. I'm impressed by the sea foam round the edges as it's not easy to do in Bryce (or so I found a couple of years ago).
I had a comment request for this - must admit, I have absolutely no knowledge of this sort of program. All I know is I like the color combination and overall lighting effect. The sky is very dramatic and impressive.
I am not familiar with TG, I use Vue myself, and I always find that TG is great for bare landscapes but that barren look is also difficult to make realistic. For example, the mountains look as if they have been cut out and pasted onto the image. The extremely strong colours give it a rather false look too. Suggestions: tone down the saturation a little. Try to get some atmospheric effects such as mist to soften the distant parts of the landscape, even a little effect helps, you do not need a thick fog. Also, try to get some spread of light from your light sources, maybe use a 2-3 degree spread. Finally, a better balance between ambient and direct light would help a little in softening the shadows. Hope this helps.