I have to agree with the negative fraction here. Mine used to work flawlessly. However, recently (for about 4 weeks) the sensor is acting purely irratic. It works twice or thrice and then it decides to reject every single finger tip I have registered for some time - only to then work again - and so on and so on.
I do have noticed that cleaning the Touch ID every two or three times in between using the home button does improve the success rate. However, from what I can read here nobody regularly, and I mean with a frequency of every few minutes, cleans his Touch ID in between usage in order to properly use his Touch ID. And my hands are perfectly clean, I guarantee it.
I'm really frustrated here. :-(