I'd have to agree with most of what's been said, so far, but I also have a slight nitpick about the nation borders.

The border of a nation usually follows major landmarks - whether they're natural like rivers and mountains, or artificial, like lines of longitude or latitude or something.

Here, most of your borders are near rivers, but don't follow them, and it causes things to look strange. If there was active fighting there, causing the accuracy of that border to be somewhat in question, then I could maybe see it, but that would probably be better served by some sort of mix of the two neighboring colours (maybe hashed lines of alternating colour or something) indicating a contested area.

Other than that, great first map!

-asp