Who are you protecting your phone from?
"but my mate here can't unlock my phone and I can! See? It's working!"
This is all most people are really worried about. If I'm worried about keeping it safe from the police or other more determined attacker I'll use a PIN, too.
The proper implementation is a print for all unlocks, with an additional PIN required after a certain user settable timeout. The paranoid can set the timeout to 0, those who only care about keeping it away from their technically clueless spouse can disable it, I'd choose 30-60 minutes so it wouldn't be too annoying but if the cops arrested me by the time I was booked and they wanted to peruse the evidence the window of opportunity to hack my fingerprint will have passed.
Biting the hand that feeds IT
