People in the Starwars Galaxies closed beta begged the Devs not to release it as it was. There were many bugs that they simply refused to fix before released.
Somebody needs send a clear and strong message to game producers: It's not okay to pressure your Devs into releasing an unfinished game.
It's safest to start playing a MMORG about six months after release if you want it to be Bug-Free (relatively), However you're missing out on learning a new game with thousands of other people.
By the time you get in.. You'll be just another newbie.
As for WoW, nobody has tested it because the closed Beta hasn't started yet.
A horribly incomplete version of the Alpha was accidently leaked, but it wasn't the Game. It was hardly playable. Basically, just moving around on a few maps.
Anybody who has claimed to have 'tested' WoW, is full of it.