Facebook launched three apps this year: Paper, Slingshot, and Rooms. None of those apps appears to have any traction.
In the short term, it doesn't matter. These are relatively small investments. In the long run, the concern is that Facebook lacks a creative spark to create dynamic new products on its own. It will have to acquire its way to a successful future.
So why highlight Slingshot? Because it was the most confounding of the apps Facebook launched. It was sort of like Snapchat, but you had to "sling" a picture back to the other person before you opened the picture they just sent you. Facebook bailed on that feature pretty quickly.