I use it to unlock my phone if it works. Won't work if your finger is wet or dirty, or if if there is any dirt on the button. Doesn't give enough time for you to adjust your finger before it gives up and goes to pin code access after third attempt. Otherwise it works pretty good and fast.
Using touch id for both unlocking phone and for iTunes. I have three different finger prints saved so I can unlock no matter how I am holding the phone. Haven't had a single misread since I turned on my iPhone 6+ for the first time
I have to get used to it after upgrading from an Iphone 5 to Iphone 5s. It has been a habit to put in my pin to unlock my phone on the Iphone 5. I've noticed the difference when I've Jail broken my Iphone 5s, I miss virtual home ever since I've upgraded to IOS 8.0.2
On a side note, during the winter, the blood flow to my fingers changes to the point that I had retrain the print reader the other day while at a store. It was just more frustration on top of a futile search at Home Depot for something they used to carry just a few months ago.