the sky is great, also the flock of birds look good. I like the foreground hill on the left, but it needs more GI samples and much higher AA.
From a compositional standpoint, I would let go of the midground mountain on the right, and remove the airboat, or place it much farther away.
So if you leave the sky as is, remove the mountain on the right so that we look onto a wide plane or smaller hills, and re-place or remove the airboat, this image would definitely be really really cool

Lastly, the tree population is not dense enough. You need 5 times as many trees at least

Cheer,
Frank