I would not recommend you to buy MoP. I quit Wow two or three months ago while it was still Cata... Wow gets cheaper with every addon Blizz releases. I just got tired from the easiness (and whiny little twelve year-olds, GOD those twelve-year olds).
But to return to the topic, I participated in the beta and wasn't too impressed. It's all new of course but if you last played BC you'll be extremely disappointed by how this game changed. I cherish the good old times (and LOVED BC) but was glad I quit. There's nothing for you there
