you might want to review some of the literature around bypassing fingerprint readers before making that kind of statement... A large number of readers are easily fooled by copied prints. Also there's the False acceptance/false rejection rate tradeoff to consider.
Once of the major issues with biometrics is revocation. If compromised it can be difficult to change!
There's also the glossy fingerprint attracting screen of the iphone. Creating an artificial fingerprint from what you've left on the screen would be non trivial but far from impossible.
Once of the major issues with biometrics is revocation. If compromised it can be difficult to change!