First I would go with the more saturated colors of the preview from blender.Then you might want to think about what story the surfaces should tell. Are they clean, used, weathered, etc. Out of which material? Surface finish?Currently it's too much randomness - cloudy spots everywhere.
doing a bit more detail work
I made it from a reference. I link it in my artstation page.The concept art itself is only color shading so it is hard to judge the material use but i plan to go for a realistic texture.