I felt quite surprised when I read the heroic encounter feedback from the official forums. Basically every encounter seemed "overtuned" and the people were basically crying for nerfs. Among these guys were people from for example glorious Paragon, Premonition and Vodka.
Another thing I noticed was that one of the only heroics that guilds were able to down during first day of betatesting was Tron council heroic, which a player from Forlon Legacy commented like this: "Super well tuned on heroic mode. Extremely unforgiving and complex in design."
I find it really ironic that top end guilds have moaned for harder content really long time and now they seem to think a heroic that can be downed within few first pulls during the first night of betatesting is "super well tuned". If the raids in Cataclysm don't seem to fill peoples difficulty-expectations, it's the top end guilds and betatesters who should take a look in the mirror, not the designers.