That image is strikingly beautiful as it is. This is an amazing render.
EDIT: I don't agree, but some peeps at ashundar think you should randomize the twist and shear a bit. I like the shapes created with the uniform twist and shear, but I'll tell you how to randomize it so you can experiment.
In the place where your twist and shear shader was, plug a distribution shader (if your twist and shear was after the compute terrain - move it up so it is before it) and don't change any of the settings. Plug the end of the distribution shader into the next node (or compute terrain, if the twist and shear used to be applied after the compute terrain). Plug the twist and shear into the distribution shader's child shaders node, remove any inputs from the compute terrain. The twist and shear shader will now only act on the areas designated by the distribution shader which, at the moment, is all of them. Turn on fractal breakup. Play with the fractal breakup shader (you won't need many octaves for this, also increase the overall fractal feature sizes and lower the colour roughness while you're at it) and change the coverage setting in the distribution shader. Randomize the seed a couple of times until you get a nice distribution of twisted and not twisted.
For bonus points you could add another twist and shear pointing in the opposite direction, and use a negative of the fractal breakup shader for the first twist and shear to control it's location. then you'd get mountains pointing in opposite directions to varying degrees.
