I've had the S8plus since launch day, and initially, I didn't lock the phone at all. since then, I've tried Iris scanner, face recognition, and fingerprint sensor, in that order. I tried Iris scanner for two solid days. I wear glasses, and while it did work, it wasn't very reliable. I'll bet I had about a 60% success rate, which is bad for this functionality. then I went to facial recognition, which I used for 4 days. initially, it worked 95% of the time, then all of a sudden, the accuracy dropped. by the time I was ready to stop using it, it was literally a coin flip's chance. so, I reluctantly went to the fingerprint scanner. I did both my pointer fingers, (I'm left handed) and I must say, I've used it for a solid week plus, and everyday, it gets more and more natural, and it's super accurate. with a case, you learn to use that to help you figure out where the sensor is, and I hardly ever hit the camera. with that being said, Samsung would endear themselves greatly by either moving the sensor more to the center and under the camera, or integrating it with the on screen home button on the front. but for now, I can handle what we have.