Cataclysm

The most noteworthy content that Cataclysm offers for newcomers to World of Warcraft comes in the form of playable goblin and worgen (werewolf) races. Like all races, they have unique traits that make them particularly well suited to certain classes or professions, but the most compelling reason to play as them is to experience the all-new zones where their adventures begin. The two could hardly be more different; the worgen starter area is reminiscent of a perpetually dark Victorian England during a werewolf epidemic, while the goblins' is almost futuristic by World of Warcraft standards, with flashing signs and marketing personnel that you can cruise past in a garishly painted hot rod. What these zones have in common is that they both feature a decent variety of quests, and like many of the other, redesigned starter zones, they do a good job of making you feel like a character of some importance from the outset, as opposed to one who starts out performing menial tasks and killing unsuspecting wildlife.
Regardless of which of the 12 available races you choose to play as, there has never been a better time to come to World of Warcraft as a new player. Not only are the redesigned starter zones significantly more fun than they used to be, but the game now does a much better job of explaining class abilities as you unlock them. For example, when you unlock the frostbolt ability as a mage, the tooltip associated with it tells you not only that it hurts and slows down enemies, but also that it's a good spell to open a fight with. And as a hunter, you're told that your damage-over-time serpent sting attack is especially useful against enemies that take a long time to kill. If you're a newcomer, these tips are invaluable, and if you're an experienced player who has previously found one or more of the 10 character classes too confusing to play, now would be a great time to give them another try. Don't bother attempting the archaeology profession with your new characters for a while, though.