Leaving aside technicalities, this can be quite a masterpiece. I love the whole concept behind this piece, I have checked the source photo and I was stunned that not everything was solely based on that.
The problems with this piece won't ruin the image depicted, but are rather cosmetics that should you have refined, it'd turned into a lovable drawing. The colors are good, and the shadows are not that bad, though you need to find your way around shadows. You need to practice shadows, even though you showed quite an adeptness through that mountain light.
The structure floating in the air seems quite interesting, it sets an entirely different mood should it not be present, though the sea of colors behind it that I believe are meant to be skies and distant mountains just kind of to bit of degree, belittled the structure.
The only interesting elements I can see here are the mountains, the structure and the radius around the adventurer, please allow me to call him that for the purpose of this Critique
Everything else on the right seems dull, and could use better tonging and a little care from your side.
Overall nice work champ, and I hope you keep learning and refining your fantastic talents!