Personally, I can't wait until the beta rolls around. What was playable at the press event seemed pretty darn far along in development, so that beta can't be very far away. I would be surprised if it there were more than a month between now and the beta testing, and I would even expect it sooner than that. Mists of Pandaria already seems much further along in development than Wrath of the Lich King or Cataclysm were when they entered beta.
The sooner the beta rolls along, the better. I'd love to take another crack at the Temple of the Jade Serpent and show the Sha of Doubt what's what.
It's open warfare between Alliance and Horde in Mists of Pandaria, World of Warcraft's next expansion. Jump into five new levels with new talents and class mechanics, try the new monk class, and create a pandaren character to ally with either Horde or Alliance. Look for expansion basics in our Mists FAQ, or dig into our spring press event coverage for more details!