Wow a black president made certainly a lot of difference. Just like the white ones : lying, deceptive, secretive, and dishonest (See NSA). Sorry if I fail to see much difference.
The important difference is that there are now millions of black American kids no longer growing up in a world where they just "know" as a first principle that "black people can't be president". That sort of example simply changes people's outlook. Inspiration and aspiration matter.
That's precisely the shakeup the world needs - to realise that whatever skin colour, male or female, people are people and you shouldn't judge them negatively or positively on how much melanin or testosterone they produce :P