I've installed this without any problem on a couple of basic WordPress sites, but I got stalled at the point of connecting my WordPress account to Facebook on my main company website. One thing that's different about this site is it's configured to force https connections for the administration screens to protect my password and other sensitive info.
When I click "Link your Facebook account to your WordPress account to enable," nothing happens. I wondered if something about the SSL setup was getting in the way, maybe because the callback is directed to an http rather than https address.
This is just a guess. If others have successfully installed on WordPress sites with SSL configured, there's probably some other plugin conflict I need to track down.