Not bad. The overall quality could have been enhanced, I think, as the clouds (especially their shadows) look rather fuzzy and the ships look kind of blocky, but the composition is definitely there. Placing populations isn't too hard in my opinion; you just have to get used to fiddling with the dimensions and density. I can understand your frustration trying to get it to fit right when it's this far above the ground, though. Also, cyphyr, you get populations above the terrain by increasing the y-value of them.