Hmm... I like the basic shapes and actually also like them to be on the "square side" .

I just googled "rocks" and watched a couple of pictures, and when directly comparing those to your rocks, there is still something that makes them look like CG.

Maybe what you need is to check and experiment with displacement mapping.
It would certainly add roughness to the actual geometry.
The more I experiment  with displacement (mapping) the more I find that rocks look significanty more realistic  with displacement checked (if I manage to render them without artifacts)

But this is just how I personally perceive it.

http://www.eonmusic.ch http://www.artmatica.ch