There's much promise in this one. There are however two things that imho are not going in the right direction:
# additional highlights on stalactits in the top-right corner bring contrast that imho doesn't fit with a background scene. Moreover, they do not work that well to improve the volume and imho rather flatten the shape.
# the river, although bringing interesting diversity, also enforce a perspective that do not work well with the rest of the scene -- esp. if you intend to see it scrolling. All of sudden, we wonder why those stalatctits/mits line up that perfectly, and why we don't see the water flowing in the river.
Both could be kept, for sure, but they'd require an significant level of polish to get on par with the rest of the piece.