Not bad! I like the shading here, especially on the rocks. There's a good sense of depth as well. I feel that the sky, once it gets to the brightest point, seems a bit empty. Other than that, the tower in the distance, and the bright green up front to give that contrast make this a really nice piece.
Also, I'm curious- what program did you use to make this? I just gave pixel art a try using photoshop and spent a good while trying to figure out why the pixels weren't exporting sharply. I found that I needed to set the quality when exporting/resizing to "nearest neighbor" in order to preserve the sharp edges. Again, this is for photoshop (as far as I know) but it might be good to look into, so these works shine to their fullest. :) Keep it up!