I've had mine for months and until last month when I bought a Nexus 10 it was well used. The battery was exhausted only a very few times but all that happened was that the device went dead. I plugged it into the charger and made sure it was powered down so that recharging went as quickly as possible. Within a couple of hours or so I was back in action. Mind you, I have a pretty well organised daily charging routine. Certainly it will function for a couple of days of light use. Great for reading in bed.
I have let it get exhausted occasionally and it is fine. This one though is a replacement for one that died the very first time this happened. Amazon were great and sent a replacement immediately and this one has had no probs so far. Hope this helps.