The colors are all looking solid, however the staircase seems to have some perspective issues, as if they are tilting down the hill midway up to the castle. Now accurately plotting out stairs that curve and arc like that is quite the chore, so I wouldn't blame you for saying "lets just not look at that".
You can fake correct it by rotating that double back on the left side about 9 degrees clockwise and filling in the gaps left behind quickly. But again if this is all about color, don't worry too much about it, the only reason I bring it up is because of how much of the canvas the stairs are taking up.
Its still not right like this, but it is a quick fix that will eliminate the perspective issue fairly well.