Facebook is probably hitting the world economy for a few billion dollars a year.
With that said, Mafia Wars and Vampire Wars are addictive and super fun... in the same sort of sense as MMORPGs are, except without the pretension to having any graphics at all past a spreadsheet. They're the sort of thing you do when you're tired and you don't want to do anything. Considering how hard people are working these days, it's no surprise such things are popular. Who wants to have to think?
"I'll just do that job one more time when the energy is refilled enough in three minutes... oh, never mind the essay. I'll do it later."
Facebook, like the entire Internet or at least most websites in general, is a tool. It's made by humans, can be abused or used for great purposes by humans, and is usually utilised by both. You can't criticise a hammer for being used to smash someone's face in, much the same as you can't thank it for building a bridge that saves thousands of people a half hour commute. (Don't apply this logic to guns though, it's different when the tool is made purely to kill, maim or hurt. Websites aren't.)
Anyway, you can't fairly criticise Facebook, nor can you fairly compliment it, past the basics of design perks (on that note, the ads are becoming a bit intrusive). It's up to the people you link with and the applications you choose to use, how good your experience is. And people can vary from ... well, Hitler to Buddha. That's a pretty drastic scale, and that's enough to blame for social issues without throwing in a website while you're at it.
