Facebook Safety Check

While many people would agree that social media sites like Facebook have utility limited to entertainment or pure suckage of time, one interesting feature is Facebook Safety Check which was designed to allow people to communicate during disasters. As Hurricane Matthew threatens the Caribbean and the east coast of the United States, I could see value in this sort of service. To illustrate, here is the Facebook Safety Check banner from the Hurricane Matthew South Carolina page:

What has been your experience with Facebook Safety Check, and have you used it to communicate with your friends and relatives during disasters?