My main problem with this picture is that Korra's midtones are much darker in the actual show. She is almost unrecognizable here because the midtones are so light. If you could correct her midtone to reflect her skin color (darker brown) which is the most basic indicator of her appearance, this would be a much better piece of fan art.
I've seen a lot of arguments like these on Tumblr, and frankly, I'm getting sick and tired of them.
I'm not going to change this anytime soon (since I've deleted the layered file for it awhile ago), but as a woman of color myself, I'll make sure to do some more research on the way lighting affects darker skin tones.