Compared to previous versions, connecting to the internet via a Bluetooth enabled smartphone is incredibly easy: simply tick the checkbox next to “Use this device to connect to the Internet” when pairing your device, and then, in Network Manager, your phone will appear as a new network adaptor.
Caveat: Network-Manager might have a preference against Bluetooth PAN so high that the connection does not show at all in the drop-down list as long as any other option is present.