I've got a couple of mates who are face-meltingly awesome guitar players. They were naturally skeptical when they heard about Guitar Hero, but after playing the game, they loved it. While it's debatable whether I'm a face-meltingly awesome producer, my experience with DJ Hero has been remarkably similar.
I first saw this game at the Auckland Armageddon Expo and i might say it looks like a very enjoyable game for any age. The game is alot simpler than Guitar Hero and has a different variety of music and aritsts. It is a strange jump from a band to a Dj but it still will be as popular as guitar hero is.