The changelog (via) is all about bug fixes, it seems, but given the number of people complaining about how buggy the Facebook client had become, this isn't a bad thing:
- Correcting problems arising from the sharing of content.
- Correcting problems arising from the previewing of maps.
- Correcting problems arising from viewing photos.
- Correcting problems arising from using files in groups.
- Correction of problems posting items.
- Correcting problems arising from birthdays.
- Correcting app crashes.
You can grab/check the update in the Store here (especially if you view this page on the phone, in which case you get bounced to the right pane in the Store client).
A few screenshots of the new version on my Lumia 950 XL below. It's good to see continual updates to this client - for many regular users, Facebook IS the Internet, in terms of extra functions beyond phone-centric features. And the Windows 10 Mobile seems to tick all the boxes. Comments welcome, is there anything major that it's missing?