It's obvious that users don't care for their friends to know where they go. Facebook is a place that people thought they could go to stay in touch with people.
If they want to check-in, obviously, there's Foursquare and Loopt for that.
Facebook is now facing a lot of regulatory scrutiny as well as competitive pressure from Google+. Furthermore, it could be launch its IPO early next year. I'm sure news of Places failure isn't a good thing for investor confidence.