I've had an account on WoW since last March, but I've only been able to play for a grand total of 35 days in game. I have a level 70 druid which is fun to play, but I'm not obsessive about it. I just get on every now and then and play for a couple hours and call it a night.
As far as MMOs in general are concerned...I'll just quote my friend:
"World of Warcraft is a great way to save money. You end up not playing any other games, you won't go out to frivolously spend money, you don't end up paying for a girlfriend, and once the next MMO comes out, you just drop WoW and subscribe to the new one."
Which is sad, because I still have an extensive amount of PS2/PS1/GC/Wii/DS/PSP/NES/SNES/GBA/PC games that I've never beaten.
Not to mention my slowly dying anime addiction, lol.