I love the enerG power bank! I'm addicted to using it.
I don't like the idea of charging smartphones when sleeping. I see that as a very dangerous thing to do even with original chargers from the smartphone. It's a 220V outlet after all and well, things do go wrong even if it's a 1 in a thousand chance of happening. But with powerbanks, I'm confident to charge my phone while sleeping. It's a safer source of power and the entire power bank shuts itself off when the phone is fully charged. I think it's really smart and safe. Really a must have for any smartphone user in my opinion.