For quite awhile, I've used the Wordbooker plugin, as it was the first plugin to do many of the things this new Facebook plugin does.
While I admire Steve Atty (the man behind Wordbooker) for his tireless devotion to the plugin, the plugin often runs into trouble whenever Facebook changes things on their own site. And for some reason, "automatic" updating via WordPress isn't recommended because it can wipe out one's settings. By contrast, a Facebook plugin made directly BY Facebook seems like it'll be updated to remain compatible with FB, and it appears it'll be OK to use automatic updating.
My wish-list for improvements:
Commenting: For my site http://www.cnyradio.com I like to make people register and login before they can post comments via the original WordPress interface. I don't want people being able to post anonymously with fake addresses. Wordbooker recently added commenting via Facebook. The way it works, I have the WP interface, and then right below it, FB's interface via Wordbooker.
I had temporarily activated the commenting feature via the Facebook plugin, but it replaced my WP commenting interface. I liked that it added "# comments" links on my front page, but did NOT like that it also completely replaced the original WP commenting interface.
Jetpack recently upgraded to allow people to choose to login using a WordPress.com login, Facebook, or Twitter. But, these options aren't visible if you only allow "registered" users of your site to comment... and once someone logs in, their comments are posted with their account on the site itself -- no option to switch to FB or Twitter login.
I'd like to see something which combines it all -- ONE commenting interface where people can login with an account from my own site OR Facebook OR Twitter. And regardless of how they logged in, all the comments should appear together, and as someone else asked, it'd be nice to see the comments posted via Facebook login mirrored to Facebook if the user desires.
Basically, I think there are a lot of people out there who want to include the Facebook commenting interface, but also need to keep the WP interface because each offers unique features, and it would be tough to go with JUST one or the other.
Also, not sure if there's already a way to do this but I missed it -- but WP has a widget to display your site's latest comments, as long as the comments were posted via WP. Would also like to see a widget that shows the latest FB-posted comments. Better yet, a widget that can show the latest comments posted through either method, so I don't need to show separate widgets.
Bottom line, I want to let people post comments via FB. But WP is also nice for people who don't want to post with their real name. They can register with a username that maintains their privacy, but also allows me to delete/ban the user if there's ever a problem.
We need something that combines the best features and functionalities of both worlds.