For MMOs in general, a lot of fun to play and a good value in the sense that you don't have time to play or buy other games.
I played Asheron's Call for 10 years. I had a great time and made some good online and real life friends. They can be a total time suck but if you figure you play 20 hours a week playing a MMO or playing 20 hours a week playing various other games, it is still 20 hours. So it depends if you want to dedicate that time to a MMO or other games. Of course you can be a more casual player and play less.
So why Wow, there are plenty of other good MMOs out their.
Like Poison said, having a good guild/group is important but some guilds can be very demanding on your free time.
Happy gaming, the Prisoner...