If you are going to encourage everyone to run through a central Epic quest line, it is important for that line not to be left in a horribly bugged state for months. I know there is the big expansion tomorrow, but if Book 8 does not work, why should I care about Book 9?
My first visit to the Hall of Mirrors had a group problem. Hall of Mirrors depends on clearing corruptions, and we had two Hunters and a DPS-traited Loremaster (no crowd control) who either could not or would not remove corruptions. Hunters cannot remove corruptions on enemies with more than half health. The corruption in question gives a massive AE HoT. You can see why we never got through that. Hey, thanks for making corruption-removal essential and then ensuring that my class cannot do it. Hunters get the bonus of being able to remove three corruptions at once when they finally can, at the cost of most of their focus, which I have found useful perhaps twice in all of Moria. Very few enemies stack corruptions. This is not strictly about Hall of Mirrors, just a game design failure that becomes important there.
I visited this weekend, and the second boss-type encounter (Morroval Task-Mistress) failed in three different ways. The first was probably our fault: the fight started before we were all in the room. Apparently the boss can aggro about 5-6 feet from the entrance, and a door closes when that happens. Hey, our fault for walking in a 5-foot radius rather than diameter. Real heroes hold hands at all times. We realized later that you could jump in from above, taking the falling debuff (slowed movement, cannot dodge, parry, or block). This become important, because the door to the room never re-opened, so we had to re-attempt it with everyone unable to dodge, parry, or block against an enemy who gets a +1000% damage buff. Having no way to avoid damage, as she was immune to any crowd control I tried, that attempt did not go well either. Then the entire instance began spawning them. As we went back down to her room, we saw a Mistress walking towards us. Turns out, much easier outside that room with no adds. She died. Then another one walked towards us. And another. And another. Four of them later, we were back to the drop into her room. She was still there, with her add. As bugs go, spawning multiple copies of bosses that wander the instance is a doozy. Eventually, the group gave up on this.
As a further note on bug reports, the little box where you enter the quest name needs some sort of instructions. This was my first time submitting a petition for help, and it repeatedly rejected it because it did not like how I was entering the name of the quest. I eventually found a combination that let it recommend what the database calls it. Not letting players submit customer service requests is certainly one way to cut down on customer service costs. Submitting it as a bug report required me to log into something else, because apparently it does not recognize that I am logged into the game. Which I cannot play as I puzzle through all of this.
Best of luck having the next expansion not be a bug- and exploit-ridden mess for most of the annual development cycle,