I'm thinking it looks pretty good so far. The one thing that threw me (mostly because my depth perception sometimes goes in reverse) was that, at first, the mountains seemed more like valleys until I mentally oriented the shadowing. Further thought led me to think that, perhaps, a bit of texture to the non-mountainous areas might give a better idea of elevation. As for the scale of things . . . I suppose one way you could decide (and sometimes I use this trick) is to pick one mountain in particular and give it a counterpart in the real world, say something like Mount Baker. With that as a basis, it might give you a better perspective of how large everything else is.

GW