The Facebook Beta app for Windows Phone is the official offering for consumers. It's the new app that's replacing the older listing that many users slated for having issues with. We last looked at Facebook Beta back when Microsoft released 184.108.40.206.
The popular social app has been bumped to version 220.127.116.11, but we're not entirely sure what's new. That said, if we had to guess we'd speculate bug fixing and minor improvements have been implemented. You can download Facebook Beta from the Windows Phone Store.
Thanks, Jiffffypop, for the tip!