It's funny that you made this thread, as I just resubbed last week after 10 months away to PvP with some friends. There were 2 reasons I left- hunters in arena ruined the entire experience of PvP, and MOP dailies ruined the entire experience of PvE. I had mixed emotions upon noticing that stampede was not the instant death button it was before (nor Avatar for warriors), because I noticed that hunters were still pretty damn ridiculous in arena.
However, I unsubbed less than 1 week after resubbing for 1 reason: the CC. Every class has multiple forms of CC- stuns, disorients, fears, etc. It's way, way, way (way) too much. The amount of time you actually spend in control of your character is minimal. In a 2v2 or 3v3 arena, this is somewhat mitigated if you run with a dispeller/healer, but for the most part it's ruined the rest of PvP for me.
It's unfortunate because I think WoW PvP could be unbelievably fun and challenging if they cut 75% of the CC out of the game. I know that GC realizes this is a problem, I believe I even read him mention it somewhere. I would actually like control over my character when playing a game where I control a character, I know that may sound odd. It used to be we whined about rogues because they had so much CC, now every class has the rogue level of CC and then some. It's exacerbated the problem.