Great!
I think the rock behind the spaceship somehow ruins the composition, the position of the spaceship itself it’s a bitt off (in my opinion), maybe too much on the right. The tree, partially hiding the ship is also disturbing somehow and there are a lot of composition tangents i believe (the two trees on the left, one touches the right edge of the canvas, the foreground mushrooms and the tree on the right are just like they rest on the bottom of the canvas. All these issues flatten the image in my opinion.
My advices are: just widen a little bit the angle of view so that those elements don’t touch the canvas borders, add some rim light or fresnel reflection to the ship to separate the silhouette fro the BG, remove that rock or move it in another, more convenient place, add some depth fog to the BG and darken just a little bit the foreground elements, also try to move the ship slightly to the left.