I think the composition works good, but the picture is too dark. The back of the cave is pitch black, i would work with some additional lights. I would although bring some more light in the gold so its nice and shiny - especially the cup in the foreground (excuse my english, its not my first language). Maybe you could even relocate your spiderweb so it goes from the rock to the cup in the foreground. Some coins that lie around would be cool.
this is an accidental double post… please delete this one.
thank you for all your suggestions. this is where I have changed the picture to for now. would love more input!
I just keep posting here, so I dont get confused (I am still a limited user so my answer take some time to pop up)
Are you rendering with Blender internal or Cycles?
The Cave itself is pretty blocky still, a subsurf modifier will help.
I think some fog will help the scene a lot, so that you can see the sunrays shining on the chest.
I saw you wondered about the fireflies in your second post: This helped me a lot https://www.blenderguru.com/articles/7-ways-get-rid-fireflies/