This plugin does not seem to work with SSL. I have WordPress HTTPS Version 3.3.6 installed and as near as I can tell, whenever the part of this plugin controlling comments tries to connect to WordPress.com, it does so insecurely. The return from this then fails (I would guess the HTTPS code views it as an injection from a non-secure location) which causes the comment to not submit.
I also have a problem with the Plugin showing up on a generic site users Dashboard. All of those different things to click on plus a WordPress.com login bar. I have to believe that would be extremely confusing to a generic user.
I've had to deactivate this plugin in order to keep my site working under SSL.