I'm curious, but the 40min demo didn't look that puzzling to me.
It seems like you go from A to B to C, like towers in an open world game, trying to avoid the baddies in between, and with the occasional scripted moment.
If MGSV is any indication, the big set pieces (like the WWI battlefield) will probably be sandwiched at the tail end of the game, and very on rails/scripted.