There's a few things that you could improve on in my opinion.

First, when you use brushes, you need to be very careful with overlappings. You've got quite some areas where mountains and trees overlap.
Second, I think your rivers are a little to straight. Especially the Dorova River looks more like railroad tracks than a river.

But for the overall effect... the sound you heard was my jaw hitting the floor! Holy moley, what a nice map! The idea with the labels alone... impressive!