The trees in the forground are kind of lame-looking. Not to sound discouraging or anything. Why don't you try simple tiles out there, perhaps with a few pointing (not VERY pointy tho) rocks.
The background, as others have mentioned could also use some major work.
Also, the resolution you've taken your screenshot in is kinda.. small, dontcha think?
The city itself is a bit squished, but you've got the general idea going, and that's what matters. You can do oh so much with the World Editor, I'm afraid.