I don't know about anyone else, but I haven't done it. I haven't even tried playing the game on Legendary. I almost never play/beat a game on the absolute hardest level, though. On the hardest level, it's usually so ridiculously hard that it's not even fun anymore.
I haven't done it, nor have I beaten it on Heroic, for which there is another achievement. I wonder if you beat the game on Legendary if you get the achievement for beating it on Heroic as well, since Legendary is harder than Heroic?