okay, those rivers are just plain badass. I love the color gradient that you are using on them. It looks very similar to to shaded relief "biome" maps that Nat'l Geo put out. I really like the subtlety of the political boundaries as well. I think you might have a style that works very well.
Suggestion: Change the landform outline from that raw umber/chocolaty color to a medium blue from your rivers, I think it will soften up the transition from land to sea.