Very nice ! I am sure that with digital magic you can remove those black spots. Maybe you like them, but I think they are destroying the synthetic feel of the picture. This crop is fine, maybe compo is a bit heavy with the dark tones grouped at the top. I tried few square crops and this works to in couple of variants.
I tried a square crop per suggestions, but cropping the bottom, not the top. I kind of like it. I thought the top was the more interesting part of the image. As for the spots, I considered cloning, but in the end decided that I wanted it to be more real than synthetic or abstract. Here's the crop: