Facebook, no doubt, has it's good points, but it also has some bad points too, as most emerging technologies do. Fortunately, we have the personal freedom to choose whether use it or not. Whether our choices are right or wrong is totally irrelevant, as it is a personal choice and one should respect that.
That doesn't mean there cannot be constructive discussion on such points, as there will always be those strongly advocating for and against Facebook and other such technologies. It is always interesting and enlightening to hear both sides of the argument anyway, as it is what makes us think; and furthermore, it is how we learn.
Just because it is very popular does not mean that everyone has to use it. Frankly, my opinion is that is rather insidious, but that is my personal opinion alone and doesn't carry any weight, whatsoever, and nor should it. Being a private person, opening up on Facebook would be difficult for me, after all, it took a long time before I entered into any discussions on IIS.