It's the only video game I play right now. I picked it up on a whim and have been playing it pretty hard lately... 67 shaman. When I hit 80, I'm uninstalling the game because it is a real time hog.
I've never played a game that had such good pacing. There is literally never down time. You can always be doing something that is productive for your character, or just fun. I remember when I got rid of my Xbox360 because I thought it was too time consuming... WoW is a whole 'nother level.