Excellent overview of TouchID and an demonstration of what it takes to bypass it.
TouchID is not a “strong” security control. It is a “convenient” security control. Today just over 50 percent of users have a PIN on their smartphones, and the number one reason people give for not using the PIN is that it’s inconvenient. TouchID is strong enough to protect users from casual or opportunistic attackers (with one concern I will cover later on) and it is substantially better than nothing.