Facebook official app on Windows 10 is now available to download. Its mobile version will arrive at anytime soon. This app has replaced the older version of FB from the store.
This app is not a truly universal app. Facebook ported the app from iOS. It is ported by project Osmeta like the Instagram app. The new version contains in-app browser, Gif for group conversations, direct messaging with live tiles and much more.
Head over here to download the app.