Maybe it's the highlight on the edges, but he rocks in the front lack sharpness. The depth-of-field (or mist) effect is absolutely outstanding though.
Very well done.
great work!
the only thing that bother me is the value from the rear rock to the back one is still to close to each other, the back should be brighter and widen the gap of the value will make it looks better.
Great rocks, especially like the towers, and how you use less colorss as it goes back, but they're closer together so it's harder to tell. Probably not realistic, but it looks cool 
Wonderful.