Another issue I've been having ever since 8.0 that I hope 8.1.1 has fixed:
My phone has been completely dying at 30% battery. as soon as my iPhone 5 hits 30% battery power the phone will shut off and it will not turn back on without the lightening cable being connected. It tells me the battery is completely dead, but if I plug the Lightening cable in, as soon as the phone boots back up it will tell me I still have 30% battery power. Not really sure if this is a software issue though (although this issue didn't start occurring until after I updated to 8.0), but my iPhone 5 is over two years old still working on it's original battery.