I initially tried it a day or two after I got the phone and did not find that it was terribly accurate. At that point I found it to be more of a hinderance than an assett. I was somewhat surprised to see the results of my poll in which I asked forum members whether they used this feature or not. Frankly, I expected that almost no one would have been using it. Over half the respondents said they were using it and finding that it worked well...so, in the interest of curiosity I revisited this feature. I programmed one of the three available settings for my left index finger and the other two for my right thumb, each with a slightly different orientation so that it would increase the likelihood of accurate "reads." Well, guess what? The damn thing works perfectly. I would say the "hit rate" is at least 90% or better with any misses being largely because I swipe my finger(s) really badly across the sensor. Hey, it's not magic after all. Anyway I now feel virtuous in that if I ever should lose my phone or have it stolen I know it's pretty darn safe.
Just figured in the interest of full disclosure I should report on my findings. For anyone on the fence, give it a try. And if you know which finger you're always going to be using, use all three of the fingerprint memories for that finger orienting your finger over the sensor at slightly different angles for each or the three available memory slots.
I don't use mine, but I don't think it's horrid either. I have found it to be just as accurate as my iPhone 5S. I'd prefer to not have to swipe my finger, but there really isn't any other way with a button of this shape. And on that topic, I much prefer the thinner bezel and horizontal button to the larger bezel and circular button on my iPhone.
I agree with the above two. So much faster and I don't have to use the pin or connect the dots.
Here is what I did. Since for the S5, you can add only three. So on the fingerprint one. I registered both my right thumb and my right index finger. On the fingerprint two I used my left thumb and left index finger. Fingerprint three I used both sides side ways and all of them works flawlessly. Oh this can be done on the iPhone as well.