It's a beautiful tool to see how your site looks like on iPhones, iPads, desktop screens and multiple Android devices.
You can rotate devices to see horizontal or vertical look. There are cool animation effects that give a feeling that you hold real devices in your hands!
It's a great solution for theme makers to test mobile layout very quickly.
Please, give us a message in issues on Drupal.org, if you'd like us to add more devices.