I wouldn't still save my fingerprint on my iOS-device. It's just not save enough.
The fingerprint may be a very specific password for each one of us, but it sure as hell is not one you can change.
I'll assume for a second that you don't know how the "fingerprint" is stored on the device. You do realize that they just lifted a print from the side of a phone and via very technical means and time were able to replicate it enough to fool the device? Forget whatever is on the device, the FBI could have framed you for murder since the day you were born. Lifting fingerprints isn't new, and your fingerprint is EVERYWHERE.
The thing is, you just aren't special enough to be targeted like this. And if you ARE that special, you are already using a strong password and knew you had a snowballs chanceinhell of being allowed to use this, let alone afraid of it.
Apple really should warn people that the system is for convenience, and does not provide strong security.
First off, how do you measure that scale you are using called "security" and how do you determine where "strong" falls? I can take a ride on any public bus here in Seattle and on just about any ride can find either
A: Someone with no password
B: Someone who does not conceal their password as they enter it.
I need exactly no skills but the power of observation to take advantage of those people. If everyone starts using their finger? Well screw that, I don't have the time, equipment, money or patience for it.
And ONCE AGAIN, if the phone is not unlocked in 48 hours, the fingerprint is no longer valid.
If the phone is ever turned off, the fingerprint is no longer valid.
Until they turn the phone off, they will need a Faraday cage so that "Find My iPhone" does work.
I'm still quite sure that the security of the average iPhone will rise by a few bars due to this.