It's a card mostly designed to make control and combo-heavy decks thrive (Handlock, Control Warrior, Freeze Mage and Patron Warrior are good examples). Meaning it's a relatively mediocre card in aggro and midrange decks. What still puzzles me is why some people still insist on running him in Rogue decks, where you're almost always out of cards by the time he's played, making him a pretty underperforming minion.