So for most people this won’t be a problem. And indeed, if you’re the type who forgoes passcodes because they slow you down, it’s better to use TouchID than to use no security at all. Also, it’s not like we’re talking about someone hacking into the phone’s secure A7 chip.
But do remember that, compared with passcodes, the inclusion of biometric access can in certain circumstances make it just that little bit easier for someone to get into your phone. And if that phone carries secrets that others really want to steal, you may want to bear this new risk in mind.