You seem to have misused the tiles a little. There should be roof tiles in the chipset (near the ground tiles) that work for roofing instead of cliff tiles. ^.^; It looks quite odd without them being used. Might want to fix that up~
Also, from the looks of it you've used only one cliff tile instead of actually tiling them properly (requires the use of more than one tile to look proper). I'll see if I can't dig up an example for these tiles.
I know they can be a bit of a hassle since they don't work like Ace ones (in that they're not autotile) but they look a lot better when used correctly. ^.^