Yeah I agree. I'm going to put more effort into the site eventually. In the short term there are details on http://blog.codereview.io and on the actual App Store page ( http://tinyurl.com/codereview-appstore ).

To directly answer your questions: it is GitHub only. I see the main benefit vs other tools is a streamlined and focused workflow for reviewing and collaborating on pull requests. Also the iPad form factor is a nice change of pace vs reviewing on your computer.