I play WoW Right now. I actually started playing WoW back in Beta testing, and quit playing it a few months before the 1st expansion was released. I quit playing it for about 6-7 years and recently came back to it about a year ago.
Yeah, the game has changed a lot. The introduction to Transmogrification has made old raids relevant again in addition to all of the new content. The addition to Arena Seasons etc was all new to me when i came back.
I play with my wife and brother in law every night. We've pretty much substituted it for T.V. If it wasn't for football, i'd probably cancel my DirecTV.
But, MMO's can envelope you. You can get lost all day in one.
That's why i treat it the same way i do marijuana. Don't do it until your day is over and you've done everything you need to do that day. Including working out.