Well there's not much on the water or land, only a few dots and lines. Improve on that. And give the houses some shading.

Thank you.
Yes, you're right, my problem is the shadows (and lights). Because of that, I always find my images too flat, not enough relief.
(And, once again, sorry for my english (I think that's the sentence that I would say most) but I'm not used to be on english communities :-/ ). )

I can imagine what most people are going to say: "Too simplistic."

Still, it's pretty big. So good job on that.

It looks very nice, maybe you could put some shadows on the buildings though?