Honestly past the first 30 minutes in which the boat to Waking Shore didn't spawn properly (EU Alliance side) the launch has been the smoothest I remember. No gamebreaking bugs, no server queues to rejoin the game after breaks (I play on Silvermoon, the most popular EU Alliance server), some minor lag the first couple hours, and ever since it's been all smooth sailing. Easy level 70 within 8 hours of launch, and already fully into dungeon runs with no downtime and no queues, with nothing disrupting the experience other than a couple of disconnects while mounted running into terrain (there seems to be some issue with that, some guildies reported having the same).
All in all, best expansion in a while. And so I go back to it. Keep all the baseless misinformation and vitriolic hate in check, it's scientifically proven that being constantly angry shortens your lifespan. The rest of us will be having fun in your stead.