As for the rock walls, I guess it depends on what scale you're trying for. Since the journey is metaphorical, the scale need not be too realistic. But if you're trying for pure realism, then it might be good to ask for a scale.
I spotted a couple small things:
- Should "Wast Land" be "Waste Land"?
- Does the path go under the Sloth of Despond? It might be good to show caves where the path goes into and comes out of the ground, if indeed that is what it's doing.
I like the overall aesthetic. The palette brings to mind both 17th century England and the Biblical holy land.