Social Media has definitely become a huge empire and made a name for itself over the last few years. But to all it a blessing, I think would be a bit of overkill. Sure you can re-connect with long lost friends, which is great, but I still don't count that as a blessing. You don't need social media to connect with people. It just makes it easier.
Social media is not a blessing to mankind. It invades a great deal of others privacy specifically those who are famous or athletes and are well known. They get their private life torn about and scrutinized by the public until they are left without any way of keeping their private lives private.
Social media, like Facebook and Twitter, is really primarily a time-waster. People are becoming addicted to learning status updates and checking sites for any sort of news. This type of connecton is not really as real as being with someone through a letter, phone call, or, best yet, in person. It also can cause envy; people are often very false online, inflating their sense of self and often posting only the best about themselves. Overall, social media is causing society to deteriorate socially.