The rivers are a little bit iffy. Be careful of having a tributary join a river at a right or obtuse angle; erosion usually causes a tributary to join at an acute downstream angle. Also, there is a lot of meandering going on, especially in the top central section of the map. How much a river meanders is typically directly correlated with the steepness of the terrain, so the impression I'm getting is that the lands are pretty flat and close to sea level everywhere except for the suddenly steep mountains. I would expect that one extremely squiggly and loopy river would just erode its boundaries and turn into a fen or swamp.

For deserts, the simplest strategy is probably a pattern of random dots, maybe with a couple sand dunes thrown in there.

Keep up the good work.

Z