Of course, the app also allows you to post to Facebook and you can also read news, giving the app a dual purpose. While digging through and explaining the app's rich feature set, the Verge points out that while it may not replicate every little thing that the official Facebook app does, it will possibly replace it completely on your phone. They even asked product designer Mike Matas and product manager Michael Reckhow if it was designed as a replacement, but Reckhow's answer was that you shouldn't have to choose between the two.
Paper is exclusively available for the iPhone in the US, ad-free, and will be available for download on February 3rd. Here's a quick overview video from IDG.