Below is an article that offers some background and explanation on the technology involved and some implications for its use.
Its easy to forget the horrible fingerprint sensors that have existed on other phones but if you choose to use the one on the new iPhone and it works properly this could quickly become your favorite feature.
I never elected to use the keypad lock available on my iPhone because its too much of a hassle to type in four numbers every time I want to look at my phone. It sounds stupid but having the lock drove me nuts. My phone would obviously be more secure with the lock activated but I have been trading a little security for convenience for quite some time now without repercussion.
The Touch ID Sensor is going to allow you to unlock your phone via your finger, literally. Even better the sensor could even be used instead of an Apple ID password so no more typing when you need a new song. Hopefully the sensor on the new Apple iPhone 5s will be all its promised. Imagine the connection possible with your electronic device when it knows you by your touch.
Inside the Apple iPhone 5s Fingerprint Sensor