I would say that it's very imbalanced. There's so much at the top and bottom that my eyes are drawn to the middle, even though there's really nothing there. I would suggest:
- Make the moon smaller and use it in the middle area, or else add something to that region.
- Simplify the top by fitting the title to one, or at most two lines.
- Tinker with the font or size of the subtext to give it less focus. Consider moving it just below the title.
- White author title running into the corner of a white cloud - it needs to pop just a little more. That might be as simple as a sharper shadow, but you might need to tinker with it still more than that.
My guideline for cover art is think original 'art' before 'cover art'. You have a moon in the background, its size, placement and circular shape are eye catching. Use that to draw the eyes to the cover and other writing. Use curved lines, lines of motion, to draw the reader's eye from the title, to the moon and down to your name.
reduce the scale for 'the' and add dark at the bottom to balance the dark at the top. it would pop more if the title and author lines were the same colour, more balance. and the byline could be one line, instead of two.. I think it may be too dark. it is pulling at the eye... I would tab it (the byline) in to attract a bit more attention to the main title and author.. have you tried adding a bit of yellow green to the sky around the moon to make the moon pop out more? that would make it glow a bit more. What about a silver shadow upon white lettering for author and title ? charcoal byline. I really like it. what you've done is great. it looks cool. should be super with a bit of finessing.