There are certain technical details I really like about this -- the blue palette, the tree shape and the cloud textures.

I think it might work better if you move the sun someplace more noticeable (I didn't see it at first glance). Composition wise, you want to create an interesting visual dynamic in how the sun, relief and tree balance each other. The darker and lighter blues don't really work, nor does the green. You have an opportunity to use the texture of the sky to create movement and visual interest but as is right now it's not very interesting.