I love the style and the idea! Absolutely stunning piece :3!
There is one thing that I find that makes this piece a bit hard to look at. It doesn't have an obvious point of attraction.
At the moment i keep looking at the statue on the left and on the right because they are so detailed and so in focus compared to the "Snake" and the guy in the middle of the shot.
I would maybe suggest you to add some more light\detailing to the snake and the guy so it attracts the viewers attention. and maybe darken the foreground tiny bit so the entire scene gets even more depth to it.
Maybe it is your next step I dont know.. but
I tried to do an example of what I mean (top pic is yours and bottom one is your picture with tweaks that i did)
I simply selected foreground part with lasso tool and painted over it with darker colour on a darken layer.
Then I selected the area around the waterfall and added a bit more white\blue to add even more depth just on a normal layer.
And as a finishing touch I changed my brush to Colour Dodge mode and painted the head of the creature and the guy and the stairs.
I hope that it gives you some alternative idea of how it can look
and as i said before stunning enviroment! <3