Clicking on the mobile theme takes you to the mobile theme. Once in the mobile theme, there is a link at the bottom "go to full site" which open the full site in a new window.
This is meant as a correction to the above post where it says the mobile will open in a new window.
The mobile version loses a bit a functionality, so you only use it on your mobile device.
If you click the full site option from your device, it will display as full site until you choose mobile again. It should default to mobile unless you change it to full site.
As of this moment you know everything I know.