It depends how you are using your facebook. If you don't want the world to know about, you shouldn't post it on facebook. The disadvantage you list could be eliminated simply by not posting or behaving in a way that would reflect you in a negative light to employers. Or, you could keep your facebook private and not allow none friends to view, if an employer requests an add simply do a "employer friendly" clean up and delete anything you think may affect your job or chances at a job. Then I see no disadvantages, and the network possibilities are clearly the advantage. In my opinion the benefit can outweigh the cons but just like with everything else in life it's all in how you use it.