Mine seemed to work perfectly at first but it wouldnt work at all the night before last.
I washed my hands, wiped the home button and unregistered my fingerprints but it wouldn't even let me register them again. Kept saying try another finger, which I tried and it still didn't work. Eventually it did and managed to register the same thumbs twice but it was still having trouble recognising me. I also tried registering it by holding my thumb head on and by holding it the way I would naturally, didn't make a difference.
The next morning it worked perfectly for a few hours then it started playing up again. Same thing this morning, it worked for a while and now it's having trouble.