I'll leave the river stuff to the river police, and the nudity to the mods (Though I doubt that will be a problem...) .
Artistically speaking, the landmasses lack a clear unity. The way the different countries/regions are filled in is so random that it is sorta an eyesore. I would suggest killing your border layers, work on the physical part of the map, and then make your regions uniformily styled (though not necessarily the same coloured).
As to the geography, it would look better if it had more contrast with the ocean.
hopes thats a start, like I said, the river people will be around shortly to help yah out with that stuff