I'm sorry but this plugin is a joke through no fault of it's own or the authors. I installed it, activated it and followed the instructions to get my API key with Facebook at the following link...
...which greets me with the following message:
Your account must be verified before you can take this action. Please verify your account by adding your mobile phone or credit card.
Are you kidding me? To use this plugin I need to release my credit card details or mobile phone to Facebook? As the plugin author, do you not think that's something you should bring to our attention before we even begin downloading it? What a complete and utter waste of my time.
Through further research it seems that verification process is fairly hit and miss: http://forum.developers.facebook.net/viewtopic.php?pid=267838
The SMS seems to rarely work leaving the developer/blogger with but one option of verification: Credit Card. Convenient considering that Facebook charges your credit card for the verification: http://www.facebook.com/help/?faq=14827
Don't take my word for it; there's a useful archive here: http://www.facebook.com/group.php?gid=125957330783122
The plugin looks great in the screenshots but to use it I shouldn't have make a choice between rampant unauthorized credit card charges and having my mobile contact sold on to marketing firms.
Granted this isn't the authors fault but it would been nice to be forewarned rather than losing time having to research the pros and cons.