Hmm, there's lots of cool hints in there,

But what about traditional storytelling, cutscenes and characters?
Sure, we talked about that when we first showed the game, but we think about the story as books.
In the straight-up campaign part of the game you’ll absolutely be experiencing stories that have a strong narrative spine, that have a beginning middle and an end.

This notion of books is interesting to me. Will all players see one strong central narrative broken into chapters? Are players each going to have different roles in different stories? Will we be seeing episodic releases of stories within the world?

I dunno, but the way Staten is talking about this is significant, and I'm interested in seeing how it plays out.

You’re in a big world that’s populated by other players, a living world where things happen even if you’re not there.

I can't tell if he's hinting about a metagame, or referencing fairly standard MMO tropes. Will there be a global economy? How will players drive the world around you? Will it be a WoW esque set of carnival rides (Instances) or use a system where players have more control over the metagame?

And for a long time we thought ‘well, we could do these innovations, but is it going to result in a better game?’ And what’s really great now, as we play the game at our desks every day, we really see that paying off. The investment is worth it.
When you run into someone in the big wide world you weren’t expecting and in the shared spaces you collide for a little while, overcome an obstacle, get rewarded for it and move on, it’s a really transformative experience.

This is interesting to me, it sounds really like Dark Souls, but can they capture that feeling? I almost never play co-op games with strangers, but I loved doing so in Dark souls, can they capture that feeling of wanting to work together? Dark souls did it by limiting communication, and giving in game rewards for helping another player, what are the systematic things Bungie is doing to make random groupings fun?