Works really well for me. It's all about perfecting the registers.
I have both thumbs, both index fingers, and both middle fingers all registered. Works fine with each one.
In case you all don't know about these finger print scanner apps...
FingerSecurity - It allows you to lock apps with your finger print
LastPassword - Let's you save passwords and log into apps automatically with the finger print scanner.
Keeper - Protects passwords with finger print scanner. Not sure if you can log into apps with it like LastPassword. However LastPassword is a subscription app.