Wow, dropping the whole simultaneous 2D/3D feature after the start is a huge, massive bummer. It could have been such a unique and mesmerizing experience to have the whole game be that way, yet they're leaving it all on the table. I don't understand why people are confused as to how it'd work, when the video clearly shows how they sync together both in and out of battle. Even if it's not exactly 1:1 100% of the time, accommodations in how things are "choreographed" on the top or bottom screen could keep things flowing in sync.
Still here for PS4 version, but 3DS version might as well not even exist anymore as far as I'm concerned.