I notice that only Twilight and Rarity have elf ears for some reason. And if I can guess, its b/c they are suppose to have the ability to use magic. I think this is better than having horns on their forehead since they are humans.
Like how you gave the human version of the Unicorns Pointy elf ears. Always thought that's what human versions of them should have. Love the style but a personal note, and its a personal one only, I always picture human twilight with slightly darker skin.