Outstanding. Realy nice render. If you want a wee bit of constructive criticism (no? well your going to get it anyway
) try turning up the AA a bit, if you look hard at the grass in the foreground it looks a bit jagged. That said, if I sit 3 ft away from my monitor, it looks totally photographic.... so I'll shut up
As to the large rock on the left, I don't think it looks unrealistic, just unusual! Makes me think of either volcanic type rock or something that has come out of a blast furnace. In fact, I have just had my boss over to look at it (he's a geologist, I work for a geotechnical site investigation company) and we are both in agreement that it is either volcanic highly vesicular rock, or klinker, from a blast furnace or similar. The klinker fits more with the colouring.
Anyway, most excellent render, have a gold star and go to the top of the class
Miles