Not a bad level at all, I found a few things you should take a look at however.
Red - Tile Error
Blue - I don't like something in blue
Green - I'm unsure if it is an error on your behalf or the tileset.
I kinda like how you are getting comfortable with unique grass styling and such, but like, I don't like those two grass-things circled in blue.
The cliffs are either mising shadows, or you are using the bottoms of the cliffs that have shadows on them. There are "shadowless" cliff bottoms.
Oh, and on the top its kinda bare. Other than that its a fairly well put together level.
(I missed a few errors, but I hope you find them.
)