World of Warcraft player? Then what are you doing reading this news article? The game's 5.2 patch is here, which means that you should either be downloading the Thunder King content or logging in! If you can't do either one of those, you can read the patch notes, the developer commentary on said patch notes, and the 5.2 class overviews straight from the horse's mouth.
Major patch highlights include a new zone, a new raid, server-wide events, new factions, and new world bosses.