The rivers that flow into and from the lake in the middle have three different places where they run out to the sea. That just wouldn't happen.
I like the font that you used in the political map, and the way that you did the borders.
The mountains have a good look to them and merge with the ground pretty well, but the ridgeline is a little too straight for my taste.
The map has a nice shape overall, and I like the oceans. It is a good start and only needs a little more work to look a lot better.