Features: New questline, involving vampires, vampire-hunters, the elder scrolls, Falmers and lots more! Two rivaling factions to choose between; Vampires and the Dawnguard. Playable Crossbows. Playable Vampire Lord. What looks like a frost giant/yeti.
The DLC will be exclusive to the Xbox 360 for a month, until going live on both PC and PS3. The price on the Xbox is 1600 Microsoft Points (~$20). No release date has been set yet.