IGN put up an interview the Associate Producer talking about the DLC coming out soon for PS3 and 360. To sum it up: It continues where the story left off, adds some powers/attacks, and is harder than the main game.

Link

What do you guys think? Sounds pretty cool to me.

...And, why wasn't this in the final product again?...

Will probably not get. Why is it that every single developer feels the need to release DLC? Either include it in the main game(or release it later, but free) or get working on the sequel.

"...And, why wasn't this in the final product again?..."

"Will probably not get. Why is it that every single developer feels the need to release DLC? Either include it in the main game(or release it later, but free) or get working on the sequel."

"What about PC?!"

Harder than the main game means absolutely nothing as that game was insultingly easy.

"...And, why wasn't this in the final product again?..."