Be careful with your brushes. You've got some tree trunks overlapping the leaves of trees in front of them, and some houses overlap mountains unnaturally.

I would rethink the parchment color. If you want your waters to be blue, your mountains to be grey, and your forests to be green, you might as well go all the way and make the grasslands green too (a lighter shade, though). If you do want to keep the background parchment looking, I would suggest toning it down to be less distracting. As it is, it's very bright, and makes everything hard to see.

I'd also agree with Freodin about the river. I think it, and the lake, would actually look good if they were the same color as the ocean.