I too played WoW since early closed beta and just recently gave it up. 2.5 years of a game is a very long time, especially with the time and effort put into it. Usually when a game like that turns to crap is when relations worsen inside the game or you find yourself most nights alone or unwilling to do things. I know that while I liked PvPing, I would never get top spot even if I tried my hardest, life you know...it gets in the way
PvE, well I got about 1/3rd of the way through AQ40 with one of my guilds, and the other guild I was in was farming MC. But after 2.5 years, I was just tired of everything. I had done everything I could do in those 2.5 years and nothing interested me. Sure there was the short term satisfaction of finishing a quest or getting enough rep to get a weapon or armor or something, but that was it, and I realized this is how it's going to be for the next year with Burning Crusade and the year after that with the next expansion.
I have several R/L friends that play and still do, but I'm done, been off it for a month now and it feels good to have so much extra time in my life to do/try other things. I'm not sure after DAOC, SWG, FFXI, and WoW that I will ever play another MMORPG.