First, I'd change the scaling of the sea background. Go into the fill styles and uncheck the "Scaled" option of the respective Bitmap Fill. You'll see that the actual sea pattern is much nicer that the tiny scaling you have at the moment.
And I don't think the enlarged village as the centerpiece works. Instead I would use the walled city or town symbol at the same scale as the other structure symbols.
Apart from that, nice work. I especially like the way you've done the vegetation and hills on the island.
You could try to put a 'beach' type border around the island. Draw an offset copy of the island with a desert fill or something like that.