Just canceled my account yesterday, actually. I had been playing since beta on various servers. Uther, Executus, Lethon, Twisting Nether, and Gurubashi to name a few. Had 5 80s (2 were DKs), at least a 70 of every class, and lonely level 60 High Warlord.
I quit because of how disappointed I was with all of the new content. The new LFG system is nice but with how easy it is for players to get geared I end up with people rocking 245 epics and only doing 2k DPS or less. ICC was dismal, at best -- I have high standards, though. Raided in EverQuest for a long, long time. Now THERE was some hardcore PvE content. WoW is a fantastic game for casual players.