Observations from my first few (buggy) hours in Cataclysm:
* Parties are still of the Wrath Of The Lich King mindset, and will not listen to boss fight instructions. It's taken deaths on the first 3 bosses of Blackrock Caverns before it is thought "Hey, maybe I should listen to those words about standing in the laser beams".
* Even when 80 people are around you, yelling and spitting at you for you to get off your mount so you don't bug the boat, one moron will still spoil it for everyone.
* People will rather camp a spawn point then join a group to do a kill quest.
* If the map location of an NPC is bugged, people will spam General Chat, even though they were at that NPC 1 quest ago.
Just another MMO expansion.