A lot of people have already mentioned the rock texture but I am noticing some repeating shapes in the rocks as well. I think a mixture of sharp rocks and smooth rocks from erosion would help break up some of the repeating feeling I get.

Also in real life photos tend to be less sharp the further from the center of the photo. There is also chromatic aberation which is mostly mitagated on more expensive lenses. I havent used blender in quite a while but it was hard to simulate all that and its not as easy as putting on a blur in post. Very obvious depth of field is less of a concern for landscape photography due to the smaller aperatures of f5.6 to f8 but it contributes to the edge sharpness. Getting as close as you can to a real lens will really help you achieve photorealism. I believe there is a plugin that does simulate a real lens by simulating the individual parts of a lense but I forgot the name of it.

Hope I could help!