Well, mostly because Alicorn Twilight doesn't have butterfly wings, glitter swirls on her face, curly hair (Twilight has straight hair! Arg...) and her jewelery should have the gems coloured. For 50 dollars they could at least paint the gems! *lol* The wings and hair bug me the most.
I have issues with the toy...if it were more show accurate I would want it more. The fact that the eyes blink and wings move when you roll her along the ground is pretty awesome. It's nice that they broke away from the old princess mold.