In order to write an essay on this topic, you'll need to have some points in favor of each view. Then you should decide which of the views you find more persuasive. Once you have decided this, write an introduction and conclusion telling why you think "your" side is more persuasive.
I would go with "marvel." To me, social networking is amazing because it allows me to keep in touch with people who I would never previously have been able to do that with. I am in touch (on Facebook) with people who I haven't seen since 8th grade, for example. I'm also in touch with many of my former students. Before Facebook, I was not really able to keep up with what was going on in their lives.