When I activate the plugin, my login screen is blank. A look under the covers show it as display: none. I can temporarily change it to display:block (using Firebug), so that I can login and try to fix it. I tried leaving all fields blank - no login. I tried just filling in the image fields - no login. I tried filling in all fields - ugly page, but still no login. In every case, I had to go in and change it to display:block in order to login again.
There are no hints as to whether we are required to use a light background, or any reason at all why the display of the login form would be hidden. The screenshot section of the plugin page is empty. The FAQ just says it's great. The Installation section just says to activate it. It is clearly broken and I'll have to try a different branding solution.