I just think it needed to be a bit more hazy... ::)
critique welcome!
It needs some work on the surface and rocks! But the lighting and environment is very nice.
i like the mood in this one (obliviously) :D ;)
i agree with dune, the ground could use some better surfacing
I see a little grain in the rays. Try turning up your atmo samples.
You've got a real good one going here. Ulco's suggestion is a good one; some additional surface work will bring this one towards some great realism.