I don't think this is going to be as much fun as it looks. So your looking for ghosts with this thing and...What? Interact with some random event with them that boils down to something like a 'multiple choice' option?
Even then, there is that whole 'wandering around' element thing the trailer shows. That just reminds me of "Zelda: Phantom Hourglass" trying to use the Microphone/stylus controls on a handheld console, and to quote a famous prick loosely, "Doing such a thing out and about, which I remind you what handhelds are for, would probably cause your own major organs to physically tear themselves from your body to escape humiliation."