For the most part the new details sound pretty good. Although I am not sure about the lack of story mode and whether a new alternative is going to be better.
Speaking of persona dancing games, I got persona 4 dancing all night recently on a sale (£7). I won't be able to play it straight away, but I am looking forward to it. It's going to be a good demo for 3 and 5. Anyone played 4 dancing all night?