DualDisc has been kind of a bust. A lot of the early DualDiscs featured long-form video extras, surround mixes, full DVD-Audio, or better audio quality that can play on a DVD player, but these days it's usually just a few videos and
enhancedstereo (which means you get a whopping 10% more bits than the CD version).
And, in practical terms, DualDisc is surprisingly dodgy when it comes to compatibility with CD players. I've never had a problem playing a hybrid SACD (yet another format adopted and then seemingly orphaned by Sony) on any CD player.
