Very good for Frost Lich Jaina, as that becomes a 5 mana, destory and minion and summon an ice elemental, so I definitely see it in mage decks. However, for other decks, I'm not sure. The card requires a combo to kill the card yourself, otherwise the opponent has control and might trade the chosen minion away rendering the deathrattle wasted, not to mention silence.
Yeah, good card for mage at the very least. I sort of doubt it'd be played in warlock though. It does work well with both Mortal Coil and Defile, so maybe as a one-of.. But as far as removal go, Siphon Soul is better for single target removal in general since you never rely on two card combos.