You know what I dig the most about that map? Those mountains. I tried something like that once, but in my addiction to detail I discarded the idea way too early, obviously. It's a really good way of showing the topography without taking away too much space for other things like towns.

On the other hand, because those mountains/hills are just lines they clash with the rivers. Maybe do them in a different colour, if you're using colour anyway? Or draw the mountains with a thicker brush. Just a suggestion.

I also think the stroke on the coastline is too thick and blurs the details.