Been reading that people have been having issues with it reading and unlocking. What I've found is if you take your unlock finger and give a solid push on the home button until you hear the click, while the screen is off, it'll unlock every time, first time.
The times I have issues with it unlocking is if the screen is already on and I just sit my finger on it to scan.
The times I have issues with it unlocking is if the screen is already on and I just sit my finger on it to scan.