The DLC will arrive via a new character called Eris, who appears in the Tower as a quest giver and vendor. She's apparently one of a group of Guardians who failed to kill the character called Crota, and has been in hiding ever since.
The new content brings with it a range of fresh stuff, including a new strike and raid (the previously leaked Crota's End), new weapons, new gear and new multiplayer maps (much of which ties in with that leak apparently showing some content already on the disk).
It's also bringing swords:
Sure, you could swing one for a bit in a previous raid on the Moon, but this looks a bit more permanent, with a shot of the blade being hefted about on Earth
The new mutiplayer maps are Pantheon on Mars, described as the game's "first truly symmetrical map", the Cauldron, on the Moon, apparently good for small teams, and Skyshock, on Earth. That's been compartmentalised to allow on-foot and vehicle combat to dominate different areas.
There's new exotic and legendary stuff too from Eris, along with class items, bounties and weapons including some of this lot:
- Necrochasm, auto rifle
- No Land Beyond, sniper rifle
- Dragon's Breath, rocket launcher
- Song of Ir Yût, machine gun
- Light of the Abyss, fusion rifle
- Hunger of Corta rocket launcher
- Coiled Hiss 1919, pulse rifle
- Time on Targer, pulse rifle
- Murmur, fusion rifle
- Against All Odds, machine Gun
- Abyss Defiant, auto rifle
Check out the full video at GI.
One last thing is that Bungie talk about seeing what people did in the game originally and reacting to that, adding that how people interact with this DLC "will change expansion two".