The "Facebook User Only" option in JFBConnect would be what you're looking for. With this mode, a new user account is created in Joomla, but is done so without any intervention from the user. You can try it on this site to see how it works. This way, it's extremely simple for users to get into your site, and every extension (such as jReviews) sees them as normal Joomla user's and they can do what other registered users could.
Hope that helps explain, but if you need more information just let us know, or check out the feature page for single-sign on:
http://www.sourcecoast.com/jfbconnect/f … for-joomla