Surprisingly nowadays people don't have much to say on Mists other than it was a "decent" expact, at least a thousand times better than WoD. Stupid shit like complaints of playable pandas aside, what do you think was honestly not so done well with it? PvE content, misc design, Blizzard's decisions, etc.
Then again, the fondess for MoP now may be a result of the vicious cycle of consumer opinion. After Legion we'll probably look back at WoD fondly.