Is the water a plane or terrain, I believe it's a plane and would look better as a terrain, it would reduce the regularity as you get close to the waterline by the buildings in front of the main Junk. The other onsideration might be to render at higher rays per pixel. Also some of the buildings on the right hand side look a little too similar, maybe alter the texture on one or two of them? Have you considered a more panoramic presentation, say 16x9 or similar to give that 'photo/poster' feeling? Now I've been critical, I'll say I think it's a fantastic image as is, but could be truly phenomenal.

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Toolset: Blender, GIMP, Indigo Render, LuxRender, TopMod, Knotplot, Ivy Gen, Plant Studio.