Works and looks great, right out the box, and the built in social sharing bar is an impressive add on.
The only thing missing is step-by-step documentation. (Currently, the developer simply directs you to Facebook's documentation, which to most users seems scarier than it actually is.)
In short, install the plugin, go to the link to Facebook apps and create a new app. I recommend bookmarking the link to the comments moderation page on Facebook, and this (not your site admin) is where you will need to approve or hide comments.
Nice job Alex. Bien hecho!
2 things would be on my wishlist to make this perfect:
1) a star rating
2) use of schema data/ micro-formats to allow the ratings and reviews to show up in Google search results
But altogether, for a free extension this is the best for general site or company reviews/testimonials in my book.