I Loved WOW first time around and spent hundreds of hours battling monsters and players completing quests and going up thru the levels...
At a subscription of $20 a month it made sense as long as I had the time to spend on it but then after a few months i started to play less and was paying just to keep my top level character alive, then one day i just closed the account it was painful but i had to do it after i didn't login for 2 months.
Last week Blizzard invited me back for 10 free days in the upgraded Burning Crusade and I have not went to bed before 3am since, nothing much changed on the lower levels: there are 2 new races Blood Elves & Draenei, lots of new monsters, increased level cap to 70, New spells for each class, entire new continent of Outland, Many new zones and high-level dungeons...
If you loved the original or even never played WOW it is worth the test drive, just download the huge 3gig file and get it free for 10 days of action!
http://www.worldofwarcraft.com/burningcrusade/