Phobotech pretty much nailed it with his review below. This is fantastic. "Dizzying" is a great word to describe this. It gives me that same feeling I get when I'm standing in front of an enormous skyscraper. The color is pretty darn spot-on too. The only thing I can think of that stands out may be a conflicting level of contrast between the backs of some of the knights walking up, and what I may see in some of those darker rocky areas closer to the view. Perhaps specifically in the lower left corner near your logo. I feel like some of the shading in the rocks could be a bit darker. The shading on the rocks further away, however, is impeccable considering the distance from the viewer it would actually be.
Either way, this is super captivating, and very well made. Great job!