Panties from an Alternate Dimension?!
So 99% of this picture has a crayon or coloured pencil drawing feel to it, but the panties are really solid and untextured. In this context, it makes them look like they're a rigid plastic object. For example, compare the bow on your panties to the ones in your hair; they look like they came from two separate works. Also, your skin shadowing is fairly gentle along your nose, thighs, under your breasts and along your neckline, so why is the collar bone so abrupt?
I know the review sounds critical, but I should end by saying that I really love the style you went with. Also, the facial expression is great; shy eyes with a palyful smile; very natural looking. On the whole, I think you did a great job on this.