My friends are completely addicted to it.
I played it, and enjoyed it, but I didn't have the kind of free time they had so I wasn't leveling as fast as them. I'm going to restart my subscription soon though, since school is close to ending.
It only gets really addicting once you make friends in it (or already have friends that start around the same time as you), and start playing with them all the time, but you have to have the time to keep up with them in level. It's gets boring when your playing it alone after a while, because it gets slow to level and the quests start taking longer to complete.
So if you have friends with the game, and time to keep up with them in level, go for it. If you lack friends with the game, you can always find some while playing it though.
If you get it, i'm Atruis on Twisting Nether, on the Horde. lvl 28, but i'm slow so you could probably catch up with me in a month or two.