I really love the lighting and colors of this photograph and the dress, but I wish that it looked more real...the neck area especially has a very digitized look to it, and I would have loved to see more of a natural look to it. Also, your (model's) eyes look to be red, which I don't think is right...Snow White has very dark brown eyes, no? But I love your take on the Snow White dress...I think it was beautifully executed. The colors are vibrant and the lacy ruffles at the neckline add a finished look. If you made this, I am incredibly impressed. Nice job. So, to summarize: Love the dress, would work on the digitizing of the picture itself.
The light/shadow balance is fantastic, and the intensity of the colors works well. Presonally, I'd tone down the vibrancy of the yellows in her overall (to keep the eye on her face/apple) - but if you don't change it, it's still great.