She looks much better when her mane and tail is actually hair and not some magical glob of colors XD Im not much of a fan of celestia but i have to admit this is very well done and your take on her mane and tail is just outstanding . Its going on my fav list.
I've said, many times now, that I love your work as a general rule. Even so, this one stands out to me. The pose, the expression, the lighting, the motion in her mane and tail - it all adds up to a piece that feels upbeat and alive. Great work
Inside of the ear needs to have deeper shadow to show depth, its shape looks confusing otherwise. The eyebrows are unnecessary and look out of place once and -if- noticed, not to mention they're blue. Wings are decently rendered, far better than some artists I've seen attempt them, but they both look like one object, the further one should be shaded deeper or something; where the wing connects to the body, a shoulder should be visible, it seems slapped on.