The scene looks great. It has good detail, an interesting composition, "cool" concept/subject matter. I believe everyone is correct you've done very well.
I would offer a critique for you though instead of ending there.
I believe the scene is lacking depth due to the lighting. Additional lights within the structure and back lighting would really help. The caverns or tunnels at the base could be lit if that is helps to tell the story your presenting. Thats just an idea take it if you like. As for the ruble at the base that could be more defined thru lighting or AO. I found that area unclear. Possible as another idea laying fog around the base so the stone like protrusions have more definitions.
Anyhow I like the image and would like to see what direction you take it next.