Looking pretty good.

How are you doing your walls? I do mine by taking the basic shape layer (textured and whatever) and copying that into a new layer above the base. Then I select the layer pixels (Ctrl-click the thumbnail in the layer stack, if you didn't know) and then choose Selection->Modify->Contract and bring it in a few pixels (however wide I want the "lip" to be). Then I hit Delete and apply a layer style to that. Copy it and place that layer beneath to serve as a shadow: flatten, color it black, blur, move it a few pixels and *then* I select the base wall, inverse the selection, and hit Delete...this is to make sure that the shadow of the lip falls only on the wall.

For the towers, I do something similar. If you look at your tower shadows (which are floating a bit) you'll see that the line of the edge is hitting at the same place on the ground and the top of the walls. In theory the shadow on the ground should be further away than the shadow on the top of the wall. I create the ground shadow for the towers as part of the wall shadow and place it under the wall base layer. Then I create a new shadow layer for the towers and place that above the wall and wall lip layers...adjust it so it seems to be in the right place then select the wall layer, inverse, and Delete so it's only on the walls.

Shadows are a big part of making a map work. You can get crazy complex by having them darker next to the objects, blur as they get further out, etc. Those things are just nice icing on your cake...getting them into the right place (and the eye knows these things even if the brain doesn't) goes a long way toward making your map look "right". Get your shadows and textures correct and people will ignore a lot of things. Get them right and then add little things like chimneys and smoke and vegetable gardens and people will rave about your map...when they realize they can zoom in and see even more detail.

Just some rambling ranting...
M