I've looked at more trailers. I don't think it looks particularly fun. It looks like a game that has taken what is usually the filler content of a RPG and turned those into the core mechanics. I guess some of it might be a little more fleshed out than usual but.. There's no real story or even real quests. Not for me.
Well it wasn't designed as a single-player RPG. It's probably quite fun when playing with others, but I doubt the solo mode has much to offer.