This picture is amazing, with the contasting colours and the attention to detail Ariel is stunning.
The first thing that jumped out at me were the eyes. They are a beatiful tawny gold, rimmed with black that I think brings out the darker side of the Disney charcter's personality.
The next thing that I saw was the jellyfish. It leaped out at me with it's colour and realism. I rember being fascinated with these creatures when I went to the aquarium. You have done it stunningly.
Alos the colour and texture of her skin along with her beatiful hair work together to create a dark but beautiful character. I love the way you have created the skin, with transperent almost invisable patterns, winding their way up her arms. Her hair looks like it really is underwater, but the one thing I would say you could improve on is the fact that it still looks a little bit too weighed down. It almost needs to be looser and more flowing.
But all in all it is stunning illustration that you should be proud of. Good job on a fantstic deviation.