I have Siri activated for use on the lock screen so I could use it with my cars hands free. Today I was helping a friend set up their new 5s. I was showing them how you can use Siri from the lock screen to open apps and if someone else tried that didn't have a finger print saved it would ask for the password first. When I pressed down to activate Siri it wouldn't even come up. Handed the phone back to my friend, they tried and Siri came up. Checked their settings and they don't have Siri on for the lock screen. Seems that even if you don't have Siri on for the lock screen your finger print will activate Siri. I thought that was a nice touch.