A lot of ppl are quitting cuz the game (Cataclysm) is just too hard for the casuals. Heroic dungeons give me a headache trying to explain wtf to do to the no0bs. I'm a tank and I know how it needs to be done and when I mark mobs and state kill order either they don't know wtf I'm talking about or they do understand what I'm saying, but don't understand why.
I actually prefer the Cata way for dungeons, but having to school SO many ppl is ridiculous. Also, like stated before the questing is now on rails and while I like the newly implemented cut scenes (instead of reading walls of text all the time) I hate being forced to go where "they" want you to go.
All-in-All it's a GREAT expansion, but I'm bored of the grind and went back to catch up on some single player games.