I've recently joined a new guild while they were doing 25 man Feng The Accursed. I've only did the fight on LFR, so I don't know much about it, or what exactly the issues were that they were having, but they said the fight is bugged. I think it was with the tanks new actionbar spells and that sometimes they wouldn't activate. I also heard one member say that he was watching a video or a stream in where every member in a raid had to reload their UI during that fight.
Is the fight bugged for you guys?