24 February 2014The Verge:
Like the 5S, the S5’s home key features an integrated fingerprint scanner, which can be used to unlock the phone or authenticate purchases online (Samsung is partnering with PayPal to enable this feature, though it doesn’t validate purchases from the Google Play Store). Samsung’s version requires a vertical swipe over the home button to activate the scanner, and we found it to be quite unreliable and virtually impossible to activate when holding the phone in one hand. It can store up to three different digits, but it was very particular about the speed and orientation of the swiping motion used — if we weren’t doing a perfectly straight swipe down, it would refuse to unlock the phone.
Doing it right is hard.