I can barely get the damn thing to work reliably when I'm watching carefully where my thumb goes. I salute you.
All these people posting about consistently unlocking it without looking seem like they're from a different universe.
My 6 worked so infrequently that i stopped bothering. At least with my 7 it works about half the time on the first attempt or two. I've put my prints in many times, I've even recorded my thumb from all sorts of angles as multiple fingers. Still no joy.
Wet hands also cause problems, but wet beyond sweaty.