I really missed the FP at the back of my previous phone. I think if you have not use one with FP at back, first reaction is to dismiss it as worse (that's what I did). In fact, it is much more convenience. You can unlock single-handed while holding/taking it out from your pocket in one single action (by touching the sensor). You dont even to need make another effort to press a button with your other hand. Your index fingers natural position is right at around the location of the sensor. So once you get use to the offset of the sensor from you index finger, I can guarantee you dont want to go back to have a sensor in the front.
I've been saying the exact same thing. It's more of a shock to people because their muscle memory tells them to reach for the "home button". Having to retrain themselves to stop reaching for the front, has them automatically characterizing it as bad. It's actually very easy to hit, and isn't bad at all once you learn to stop reaching for the front.