Except IME it's not very good because (with a 6S) you have to hold the phone very low to reach the home button comfortably enough for a double tap (which is lower than extending a bit for a firm press), which makes the phone top-heavy and much less hand-safe. I've dropped my 6S a lot, I've probably dropped it more in the few months I've had it than I dropped my 4S (at all)

I expect a Plus has an even worse hold and I wouldn't be able to use it 1-handed at all.