Unless you are portraying actual characters from the book, I would remove the wings from one of the figures, that aspect seems overdone here. The wings on the human figure are less believeable, they look stuck or painted on, so I would clip her wings, so to speak. :^) I'm not sure what's going on between the two figures either (although I can't think of a way to fix that, sorry), I can't tell if the human figure is trying to pet the unicorn, touch the horn, or is just gesturing magically toward it. What's the story you're telling here? If you're just making an image, this is less important, but the cover illustration for a book should make it clear what kind of story is inside. Also if the background is misty enough for fog at ground level, I think there should be some haze in the distance fading up into that pretty sky to give the whole pic more depth. I'm actually finding more to like about this image than not. It's a VERY good start.

This is not my "second childhood". I'm not finished with the first one yet.

Time flies like an arrow; fruit flies like a banana.

"I'd like to die peacefully in my sleep like my grandfather....not screaming in terror like the passengers on his bus." - Jack Handy