You could be a vampire in oblivion but not a werewolf but in skyrim you can be both. The werewolf feature is powerful as you can usually kill a person in one hit and when you do normal running you are on your hind legs and in sprint mode you drop to all four. You can only turn once a day and it will last as long as you feed on a human otherwise you'll turn back to human mode. The only downside is when in werewolf form you cannot loot.
Oh and another thing, if you drop an item it will stay there unless a npc comes and asks if they can have it. One of the coolest features now is in your house you can now add or remove books to say your bookcases or weapons to a rack. Lastly and I really like this one is when you kill someone you can drag their body to a hiding spot or to toss them off a cliff or bridge.
Speaking a bridge the water in the world now has a current and sometimes rapids so you can now float down the rivers while drinking some ale or wine lol