There is a couple things that stick out to me:
1. There is a lot of detail in the foreground and less in the background. In essence that is how it's supposed to be but I feel your background rocks start looking blobby. They lose all shape and form, it just kills the illusion of rocks.
2. Your sky is pretty but there is curving lines near the top of the sky that gives the illusion that this picture was somehow taken with a warped lens. I think this is what you are going for in the grass as well but its less evident. I would push the grass more to reflect that. Keep it up I think the sky is my fav part part of this piece.
SeanZ
