I started playing EQ2 almost 2 years ago and I still love this game!
Not only is it huge (and constantly growing), but it is endlessly replayable. Although the original game will keep you occupied for a long time, I would recommend holding out for the next expansion as it will doubtless include everything else that came before it, for the same price.
A couple of warnings -
This game has cost me an absolute fortune as I have upgraded my system significantly since buying it. It runs just fine with a standard set up (1GB ram is the big must-have), but who wants to miss the gorgeous sunsets in the Commonlands and the swishing of their Warlock's robes as they run away from maurauding Orcs because they are running their graphics at lower settings to reduce lag?
Secondly, I no longer have any real life friends, as all of my spare time is spent playing this game.
If you like adventure, exploring stunning landscapes, killing innocent badgers & staying up all night in front of your computer, then you must buy this game.
Please bear in mind that there is a monthly subscription fee.