Official Facebook app for Windows Phone updated with new UI
The new UI makes the app look essentially like the Facebook apps that you'll find on Android and iOS. The News Feed looks the same; the app has the same left-side navigation drawer, and right-side chat list; and, it has the same Facebook buttons up at the top that you'll see on any Facebook property. This is 100% a Facebook app, but definitely not a Windows Phone app.
The update does add support for Timeline support and more, so it's getting a solid feature set, but the UI will definitely stick out like a sore thumb on your WP8 device. If you want to give the app a try, you can grab the update from the Windows Phone Store.