Super Apple

Now, let me preface this with the reality that I'm biased in favor of this image. I think the hair is fantastically done and really shapes the impact of the image from its dynamic shape to it's powerful glow. The way the outline of the hat and ribbon really cut into the glow is extremely strong as well.
In all, I like the concept and the execution.

As my eyes travel down the image into the darker parts I find myself losing the original power of the image due to the color and method in which the underglow was executed. I feel like some more contrast could have been used to maintain the strength of the image without detracting from it. Another option may have been utilizing core shading techniques.
The last thing I'd like to suggest is cleaning up the glow a bit. This could have been done by either smoothing it with more airbrushing or adjusting the angle of the stroke to better complement the flow of the image.

Once again, I'm very fond of this image. Good job.