It's hilarious that this "official" Facebook planning which boasts of 14 authors (Facebook and Automattic among them), is rated 2.9, while Otto's original SFC is rated at 4. That's more than a full class' difference!
While Otto is actively driving people from SFC to this plugin, some of us just hate this arrangement because this plugin lacks some critical functionality (at least based on the plugin description).
Most important missing functionality: Facebook authentication. All sorts of applications (e.g. Disqus) can recognize whether or not someone is logged into Facebook and can authenticate based on that. No registration required. Only need to Okay the permissions to the app on first use, and that's that. Seamless (almost). It's a shame, nay travesty, that this is not available via this plugin. This should not only be available, but in fact available as a widget so that FB login button can be placed anywhere on the site.
Also missing are important Facebook Social plugins like Like Box and Face Pile, but I suppose that's for another topic.