I hope for Samsung users' sake that this isn't how the S5 will implement fingerprint scanning:
Recently, most of the rumours pointed towards the fingerprint sensor being built into the actual display but that’s not the case, because Samsung has implemented the sensor into the Galaxy S5’s home button. Oh, we would also like to confirm that Samsung hasn’t opted for on-screen buttons and is still using physical buttons, like it has been using in the past on all of its flagship devices. The sensor itself works in a swipe manner, which means that you would need to swipe the entire pad of your finger, from base to tip, across the home key to register your fingerprint properly. Also, you would need to keep your finger flat against the home key and swipe at a moderate speed or else it won’t recognise your fingerprint
I'm sure swiping your thumb(?) across Galaxy's home button with one hand is going to feel completely natural…eventually.