To start, I like the colors and layout.

I agree that zoomed in the borders are a bit thick. That said, I really like the coastlines and how jagged and intricate they are. Makes it fun to look at. I also have, and sometimes use the same set of brushes you're using here. Some of them, though, like the skull and crossbones just don't look good. The eyes on it give it a "teehee" look that is just weird.

One other thing, I'd stick to either the red dots for towns or the icons. Having a fuzzy red splotch under the buildings looks off.