It's a better Doom Blade although it's more restrictive. Yeah, you need two Vampires, but in a Vampire tribal deck, that's a pittance. I personally love this card since it's both creature removal and lifegain, so it helps you stabilize in two different ways. The flavour fits, the mechanics fit, the power level fits; it's just a great card.
Pros: Omni-kill spell, lifegain, cheap
Cons: Requires two Vampires