Great painting
The nudity really doesnt matter to me in the least... However I think you did a great job with alot of the features and shape of the body, as well as the environment surrounding the woman.
I believe I know why Bigbadguy finds that the essence of the Na'vi is sort of missing in the picture: Her expression and posture doesnt really reflect the mystical thoughts the Na'vi have, but moreso focuses on the lust.