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.