First, the body is beautifully rendered, along with the ocean. However, the body and ocean having so much detail is a problem for storyboarding, as professional storyboards are generally far less detailed, even for live action productions. (See: https://www.youtube.com/watch?v=JE26E4IM_-g) As far as composition goes, The symmetry of the composition lends the image a sense of weight and grandeur, though the rainbow being slightly off center vertically and very obviously digital (while the rest of the piece looks more traditional) messes with that; it looks like something of an afterthought. However, the cloud placement and the pose, help add some subtle asymmetry, which adds visual interest that a perfectly symmetrical composition couldn't. However, the angel's wings are cut off by the top of the page in a way that looks as if the image was poorly cropped. Overall, this is excellent. I'd suggest drawing the rainbow as more of a white beam, centering it vertically, and moving the angel lower on the page so the top of her wings isn't cut off. Your work, as far as anatomy and shading is concerned, is definitely at a professional level.

Hey! I can see that it is sometimes hard to get feedback and help, but I try the best I can. I haven't done storyboarding and I'm not a any kind of professional. But I have few things that might help you. First one is, that it might be easier to get feedback and learn about storyboarding if you draw an actual storyboard. Maybe like one page, with multiple images and a actual part of an story on it. Then if I look this drawing, whitch is really good, character is very well drawn for a hour's practice, I would add some story value on it. Is she going up or down? you can change it by making her look eather up or down. Then I would try to tell more about this character, is she an angel? or a superhero? outfit could help the viewer. Hope this helps and good luck. You have good sketching skills.