The rivers are fine.

If there's a flaw in the mountains, it's a style mismatch. The coastlines are crisp and clear, the rivers simple line work, and the roads nice and diagrammatic. Then you add shaded, raised-relief, somewhat fuzzy 3-d mountain chains... They just don't play nicely together. A simpler caterpillar-ridges look might fit better. Or even something like what you have, washed out to be just a background texture?

Detail isn't bad in and of itself. You're working with a tool that does layers, right? Add all the detail you like and segregate different types on different layers. Then output a family of maps, each tailored to a certain purpose.