In all honesty, I can't vote yes or no. There are many ways that this game can both benefit us and drag us on mentally. I know and have experienced both the good and bad of the game, and despite all that, I can't draw myself to a conclusion.
For most of my gameplay, this game has caused me a lot of stress that's led on to RL. Just like Davy, I found myself being preoccupied with many game-related situations when I shouldn't have been thinking about them. This habit of sitting in front of a computer screen to kill animated skeletons and socialize with people online took away time that I think, at some points, could have been spent doing more productive things.
But, at the same time, this game has granted me a wide array of experiences that I wouldn't have been able to undergo anywhere else. Through this game, I've learned more about people than I feel many people - especially my age - will probably never know. Not going into detail, the diverse social aspect as, more than anything, shown me how much some people look at a game for personal comfort - to be the great equilizer of their lives, the one aspect that makes or breaks it. Because of the diverse people that I've met, I've learned to be more tolerant and considerate of other peoples' stories and lives - a lesson that, at this level, I don't think I could have acquired through RL alone.
I've also learned valuable leadership skills that have added onto my RL ones, not only because of the very different scenarios that I'm more prepared to take on, but also because this leader persona that I have in the game - as a former GM and Officer of many guilds - is continuous for me. Because I've always found myself helping to lead someone's guild, they're just more and more leadership skills that I build upon, situations that I could easily apply to RL, and simple lessons that I'm continuing to learn. It's little things that leading a guild that find some essence of itself assisting me in RL; I wouldn't be surprised if it's like that for other people, too.
And how can I ignore the friends that I've had the pleasure of meeting?

There are countless people that I'm not even going to bother to list off because I'd exceed the character limit that - in some way or another - have helped me. I'm not talking about the complete dependency on game-friends kind of help; I'm talking about the simple gestures of friendship to the more difficult to ignore - the random conversations in chat to the inexorable spirit of always being there for each other. It's things like the former that, for some, have found for us the latter in some people. The people that we've met may only be online who we'll probably never meet, but they're still people and we can still bond. No one's all good or evil. And the neat thing of an online game is that for the people who've stuck by us and have been there to support us, we, for the most part, develop a deeper connection to them. Even if you don't meet, they become a more significant part of you. And even though it's never a good idea to get too crazy about online people, never take for granted the fact that they're people just like you and I and have the potential of influencing your life in some way, no matter how small.
Now, my good reasons drastically exceeded the bad. But, that's just based on myself and doesn't mean that I voted yes. I do not regret playing this game for the reasons stated above, but I've fallen subject to a lot of the different consequences that this game can cause for some.
Overall, the game can be great for you to escape from reality and kill some skeletons; it can also be a good place to try new things such as lead a guild. But, if it's played in excess and is more or less the center stone of your life, then we have a problem. Despite all of the good that can come out of it, it's still a game and should NEVER find itself listed before RL on your priority list.
The game's what you make it. Whatever you get out of it is all your own. As long as the one playing doesn't play in huge excess, rely too much on it, or trust people too readilily, it can be a good thing. Then again, what game is ever 100% good?