I've eaten it before - it's a dark meat, more like duck than chicken. Not bad.
When I lived in Arkansas some years ago there were several people around raising them for profit (I think some of them wound up eating some $5000 birds). My buddy was a meter reader for Arkansas Power and Light, and one farm he went to had emus in an enclosure. Of course, the meter he needed to read was on the side of the barn inside the emu pen. One day when he went in to read the meter a big male bird took offense and attacked him, striking at him with its beak and trying to kick him. He had to beat it off of him with a pair of linesman's pliers, and thought at first he had seriously injured it or even killed a very expensive bird. He got out of the enclosure and directly the emu got up and shook it's head a few times and went on about doing whatever an emu does.