I used a non-raid geared group, and while I had to pay attention, it was doable. It took entirely too long to do, especially for the amount you have to clear before you even get to the first fight.
Some notes... the trash stuff is mezzable. But the adds for the main fights are not. Thus, you can use a mezzer to blow through to the main fights, but it will be useless for the adds.
The adds how ever ARE rootable. I had good luck using a shaman and necro to push-root the adds off the tanks.
The pathing is of course goofy in many areas. I do NOT recommend trying to invis to the main fights, there are traps wandering around with a rather wide aggro radius.
I generally take 2 tanks (or a tankable pet) since when the adds spawn the damage spike might take down the main tank....the mage's pet did well in that situation.
Done this task 4 time sucessfully, took 3-4 hours. How ever I tend to move cautiously, and as noted have group geared toons. I am sure better geared groups can mow through this task is 2 hours or so.