Nice, clean looking map! It looks as if it almost blends together with the skybox - which is cool, but it makes it hard to focus on the map while you are flying in the air. You might want to tweak your light_environment to make it "pop" a bit more, contrasting the skybox. This could maybe be done by making the light a bit more white. It also looks like your ambient light level is kind of high (if not higher) compared to your brightness level in the light_environment. Otherwise it's looking good!