Well obviously its first and foremost, just a game, not playing wont kill you, make you ill or affect RL in any way.
Unfortunatly its a very addictive game, when a game becomes an addiction you realy have to step back and look at what your gaining from being in wow all the time, and missing in RL (though sometimes its not alot). At the addiction level i guess the game then is a lifestyle.
Keeping a balance is the essential part, i know people who quit there jobs to keep wow playing at a maximum - a point to which i think the game has become like crystal Meth.
There is such a thing as a game thats too good! (like crystal meth again!
)