After reading the first response to your question I'm going to ahve to agree that I think WoW is on its way out as an mmo. I used to play and it's going the path of starwars galaxies in that its making the game so "fun for everyone" that things like raiding have become basically a joke and alot of people have left because of that. I don't really know the new expansion that well, but I heard that the new raids are going to be more difficult so maybe that will be a saving grace.
The game itself is as everyone knows very prone to addiction, with the added achievements even more so. When I played I really enjoyed playing it, making friends with random people you'll never meet, raiding, arena, pvp; the whole works. Getting to 80 with one character is going to be important if you want to stick with the game because it opens up alot of other options like arena and raiding that are going to keep you interested, but the pre80 content is still good especially the first few time through. What gets you through your second character is meeting people on there that are going to keep you entertained while you do that same quest you've done before. That makes it more of a chat room with a game attached to it but really fun none the less.
My suggestion is to pick up the original and start playing it, you have while until you can get to the expansion material anyway. If you make i to 60 I'd say you like the game enough to buy the expansions.
*oh and response to the comment above that says WoW players have no friends is bull haha I started in highschool and didnt tell anyone, believe me nothing changed. Kids that are like declared wow players and like ahve WoW folders and bring their laptops to school to play everyday at recess or something, they have no friends
