I don't remember if any of the links had this info already, so I'll post it anyway.
Per GameInformer | Issue 231 | Date July 2012
(My thoughts are in white):
Vampires:
1. "Each fort will provide the player with unique benefits," says Carofano. "The Dawnguard will build new weapons and armor to fight vampires, including crossbows. The vampires can grant the player bonuses to vampiric powers and give blood potions, which heal and count towards feeding." Kind of kills the whole "thrill of the hunt" for me, but I can see the blood potions being a helpful tool for those who aren't used to playing as a vampire.
2. "Townspeople will attack a vampire lord on sight, though this no longer happens if you are just a "regular" vampire." - Does this mean at Stage 4, the Townspeople are no longer hostile? Do we finally get to blend in?!
3. "Players can exit the vampire lord form at will, unlike the the werewolf form." HAPPY!!!
4. "One ability, vampiric grip, suspends an enemy in the air with telekinesis as you drain it's health. Other powers include hovering above the ground and turning in to a swarm of bats." Can't wait! Feels like Dracula a bit, minus his giant wolf form.
Werewolves:
1. "Own unique perk tree, complete with abilities with names like "animal vigor" and "savage feeding." One power, called "totem of the moon," let's players summon ally werewolves with a howl." I may have to play as a werewolf. These perks sound amazing.
Something I found interesting:
"By killing foes with your powers, you can continue to learn new vampire and werewolf skills. This approach means that all players can see what these forms offer, despite the fact that gaining standard perks might be difficult (or impossible) for high-level characters." So does this mean high level characters are screwed?