Seeing Andrew price’s new “acadamy” i wanted to try something similar and produce real looking rocks, but i just can’t get the feel totally right after quite alot of tweaking and im in need of suggestions, If someone wishes for the .blend ill post it. 
yeah, blendfile would be great, and a little descripttion of the scale your aiming for. Is it like far away and huge or like only 10 m away?
I think you should add a displace moddifier and maybe lower the spec a little.
I made a tutoriual about this a while ago, you may find it usefull :).
Take a look here: http://luksdm.blogspot.com/2009/06/low-poly-rocks-timelapse.html
For one thing, it looks like a blanket thrown OVER rocks. Either you need your shadows to show through more, or you need to separate the rocks a wee bit.
try AO, then also turn up the spec map, and then also mess a little with the lighting (as the guru says, its 90 percent lighting, 10 percent everything else)
Lighting is normally the issue, also try environment lighting