Funny behavio(u)r on low battery (<10%). Operation slowed to a crawl (unlocking took so long that I thought it had already died until it beeped). Screen update slowed down and halted so that at one point the screen remained for several seconds alternating horizontal bands of black and the image that had been on screen. Apps running: Messages, Clock, Calendar, People. Charge was 8 to 9% at the time.

Edit: instant recovery when power was applied.