I think you should have used a little more noise after the basin fill and before the incise flow and cut back on the incise effect a bit. Often, a bit of precipiton erosion will help to reduce the umbrella-rib effect of too-deep river channels.

A key to define the meaning of the lines, numbers on key altitude contours to help judge things vertically, and a scale horizontally would be helpful. The basic shading looks nice, though.