The on screen slide to unlock button. Works perfectly on my Z3c and I'm hoping to not lose such a nice feature if I upgrade to a Z5c but it sounds like I might :(
Alright, I just tried that, and I do get the "Device will remain locked until you manually unlock it" but the fingerprint scanner still works fine. The only time I've seen it forcing me to use the pin was when it couldn't scan my finger 3 times in the row(which doesn't really happen, the sensor in that thing is really accurate(or really forgiving)).
That's a shame :( It'll be interesting to see if Marshmallow with its official fingerprint API changes the behaviour as handset manufacturers are implementing fingerprint support themselves in Lollipop (and so its going to be a bit all over the place).