I can't believe I hadn't seen the rest of these. Smh. Anyways, down to business. The concept is phenomenal. I adore the complimenting shades of purple. None of them overlap in a way to hurt the eye or offset the picture. The curve of pony Twilight's nose is just a taaaaad bit offsetting, (not sure why, just nitpicking) and human Twilight's eyes seem a smidgen too far apart. (Again nitpicking). Also, I kind of want more stars or maybe a constellation to fill Twilight's background a bit. Just because, compared to the others, this one looks a little more plain.
Other than those little things, this is a fantastic idea. Love the gleaming from her horn and hand and going across her thighs, beautiful touch and her flowing hair and pony Twilight's facial expression just seems to work. Both facial expressions scream "Proud Student" in their own correlating ways. Great job!
Let me start off with the human Twilight Sparkle. I personally imagine Twilight Sparkle with a darker skin tone, but that doesn't effect how well this is done. Like other drawings on dA Twilight has preppy clothing that I love. You have have nearly perfected that. Her sleeves flow properly and the vest fits her like a glove. Even though I prefer her to have a longer skirt (lol) the skirt is not awkwardly positioned, and is very well done.
As for the pony version there is not much to say. YOU ARE WONDERFUL AT DRAWING PONIES. I love the contrast of human Twilight's high - strung expression to pony Twilight's calm feeling.
Great job and keep up the ponies!
PS I have a small request: could you do Spitfire, Baby Cakes, Vinyl Scratch, Octavia, or the CMC as one of your next ponies in "Elements of Awesomeness"? Thanks!