Amazing artwork! I really love the dark atmosphere with that spot of light sky between wing and torso and the dark clouds all around. Also, the glowing traces from the eyes are amazing. It seems quite powerful and scary to me. The playing with light and shadow on its back is interesting too. Somehow, though, the feathers behind him, as FE-W said look a little odd, maybe because they don't quite fit perfectly... not sure about that.
Nice gesture and good use of space! Only the feathers behind him feel a bit detached in my opinion. A more visible neck would have been awesome too, the position of the head looks quite close to the shoulder, but that is personal taste. Overall good design and movement, nice work!