I have to disagree Egami, while the Duscae demo gives you a better idea of what FFXV will probably be about and how it will play (though the finished product may end up being radically different in that part as Tababta has hinted it may be) I feel the Platinum Demo did more to make one curious about the series. It basically makes you ask questions and gives you just enough information to keep you curious whereas the Duscae demo convinced enough people what to expect.

I feel a demo is really more of the interactive mediums version of the film trailer and basically the original demo gave away too much while the new demo is that cool teaser trailer that is just so weird and out there that you can't help but be curious about it.