Players are of course salivating at the idea of exploring the first new content we've seen inWorld of Warcraft since Patch 5.4 dropped well over a year ago. That being said, it's worth remembering that there are always issues on patch day of a big new patch like 6.0.2, and also that this particular dungeon is a special case - it's a dungeon that will ultimately be for level 100 players, and we're getting a taste of it now at level 90. So it's worth keeping the following in mind.

• You can't just zone into level 90 UBRS, because the instance portal is for a level 100 character - you have to use the LFD tool.
  
• There's a bug that means you can't queue for UBRS via the LFD tool unless you meet the dungeon's ilevel requirement of 510.
  

So remember, when you're trying to run UBRS when the servers come back up, please keep these two facts in mind, as it will make your experience more pleasant. And also remember, this is new content tuned for ilevel 510 and up - if you've been steamrolling Mists of Pandariadungeons for a while, those were tuned for much lower gear requirements. Maybe slow your roll a tiny bit until you get the feel of the place.