If you manage to net yourself three wins in unranked play, you'll earn a free mount in World of Warcraft, which while undoubtedly set to become hugely common in short order, is a nice way of tempting new players to try out the long time MMO giant.
However beyond a quick return to WoW, the game also offers other incentives to keep playing. Knock up 500 wins with any character for example and you'll get a gold border for their portrait and some new animations for when they cast spells or perform other actions.
If you haven't tried Hearthstone yet, it's a collectible card game, with turn based, non-interrupt action, making it fast paced, but methodical, letting you think your your strategies without bogging you down with lengthy turn phases.
If you want to give it a try, you can download it for free here and remain competitive without spending a single penny.
As a heads up, Blizzard did apologize in its presser for the lost productivity. Apology accepted.