I have one or two ideas for you, totally free of course.
-Make two or three layers for the buildings, so they overlap in some places. That way each building gets its own bevel and doesn't clump up that much. Try experimenting with some different layers on the wall rubble too to make the stones separate more.
-Since it's been in a siege, why not adding some burned patches to the buildings and the terrain.
-I think some foliage, trees and brushes and some high res grass textures would make it pop.
-The drop shadow on the houses are too far away, they seem to be floating a bit.
Nice work. Cheers