I remember different players writing about their strategies, probably in Wowhead comments section.
It was clearly, like all things, easy for certain classes/specs and impossible for others. I’m not that great of a player, but didn’t do all that bad on a Holy Priest. I did better on Ret paly, and even better on Feral kitty. I didn’t finish it.
I read that Hunters and Rogues could go in with their eyes shut and one arm tied behind their back and do it without breathing. 