I left WoW in January, after on and off playing since it came out in Europe.   
It's a weird feeling - i've lost something that, basically, defined me. Everything i've done was assinged to this game, i even made my work shifts around raid times.  Playing other games was hard, since every second i've spent in them one thought wouldn't leave me: "I could be farming in wow right now, i'm loosing time"
But now i'm free. I can do whatever i want.
But i'm still reading mmo-champion and wow.com, thinking of what i will do in Cataclysm. 
Still not sure if that's good or bad.