iOS 9.3 is coming in the Spring and will introduce Night Shift as well as a number of other new features.
Facebook Bringing Chat Heads to Its iOS Apps, Updated iPad Version With New Streamlined Design [Update: Live]
The Verge got a hands-on preview of the new app:
Within the Facebook app, you can pop-out Chat Heads for your conversations, but they won't work anywhere else because of the way that iOS keeps apps sandboxed. Just as with Android, Chat Heads pop out on incoming Facebook Messages (but not for SMS), or you can open a new one directly yourself. You can drag them around to reposition them, and when they're open you have immediate access to your conversation on top of whatever you're doing on Facebook. On the iPad's larger screen, Facebook has decided to array them vertically on the left instead of horizontally across the top.
Facebook has implemented 'Stickers', which are large emoji-like images that can be sent to friends. There is also a new 'store' where users can download packs of stickers. The company has also redesigned its iPad app, streamlining and optimizing it for the iPad's larger screen size.
Update: Facebook 6.0 is now live in the App Store. [Direct Link]