Cataclysm was a great expansion to play a shadow priest in, but if what we learned at BlizzCon 2011 is any clue, playing a shadow priest in Mists of Pandaria is going to be a whole lot better.
I know those are big words, but when we start delving into the new-for-MoP talent trees, I feel these new talents will back those words up. We're getting a new playmate for our Shadowfiend, a whole new talent tree with spectacular new abilities, and a new, RNG-free mechanism for Shadow Orbs and Mind Blast. And, oh yeah: Pandaren can be shadow priests.
Excited? You should be.