It is very dark, but that could work if there were some small light sources close to the ground around some of the machinery. Plus some textures with ambient details like windows on the structures would be good. This would help give you more of a sense of scale, which is what this is missing. Adding something detailed in the foreground, like a mountain top, a thopter, or a piece of one of those buildings close up will definately create more depth and scale. Physically increasing the size of the terrain and the models also helps. Think of the camera as the size of a man's head, increase the scale of everything until it is in proper proportion to the camera and things start to look more real. You've got a good start here, all you need to do is tweak and fine tune it to make it a great image. I'm a long time Dune fan too, I've read every book. So if I like it, you know you're doing something right. ;-) Long live the fighters!