This is beautiful! Love the composition of the elements as well as how the overlay plays into the mood and feel. The texture adds to the dusky/mysterious mood. Love the that lone, knarled tree on the curve of the hill and the three nightbirds doing an aerial dance around the moon. Very artsy.
I love the simplicity and depth that the grungy layer adds. It's as if the birds are in an aerial dance. I like the invisible diagonal line that connects them to the tree. Fabulous silhousttes. (are the birds a PS brush? I have a similar one)
I think the secret with overlays and textures is knowing when they will enhance an image. This is one of those cases where the initial image was good, and the overlay just makes it better.