Useful thing 1

Find it awesome that there are no items. The cable is integrated and I've even taken into account that the battery from the energy storage capacity is quite small. It can not fully charge my smartphone but since I'm on normal working days around 8:30 from the house and around 21:30 am back, it goes on the way back just a bit to load so that the phone does not go out in spite of music / video / chat etc. so I can be reached in an emergency and can always look on the D-Bahn app what to do is in train delays, etc.
So if you are not need a battery that can fully charge your cell phone but only one for recharging in a long journey, the device is very convenient and you can forget anything.
One point deduction because I think at the size you certainly could add something more energy storage.