We expect E3 trailers to be showy, bombastic, and entirely unlike the actual game they're advertising--that's how it works. So I have no idea what Sony Online Entertainment think they're playing at with their H1Z1 E3 trailer. It's clearly little more than lightly-edited snippets of gameplay from an early development build of their free-to-play open-world zombie 'em up, janky animations and all, with some text and a song over the top. Haven't they heard of E3 before?
SOE have shown plenty of H1Z1 before, so what do we get out of this? We see their vision for the game, beyond 'DayZ but a bit different,' and their idea of tone. At this stage of development, it perhaps says more about H1Z1 than H1Z1 itself can.
While DayZ is, for most people, "Spawn; live for a bit; die or get murdered or get tortured then murdered," H1Z1 is positioning itself as a bit friendlier. If we're to believe this, more players might actually survive to do cool stuff--driving vehicles, building bases, and whatnot. SOE's vision is for persistence to mean more than just what's in your backpack, actually changing the world, and they want players to join together to make that happen.
Not shown in the trailer is how they hope for a barter economy to spring up. If DayZ is about surviving the first few weeks of the zombie nightmare, H1Z1 is looking more at building communities in the months that follow. It's far too early to tell how all this'll work out. The game looks rubbish in this trailer, but, well, that's because it probably is right now.