Pros: Is very useful to have a usb battery charger, because working in the office, you nearly allways have a computer near, so for charging AAA and AA batteries, for mp3, wireless mouse...
Good for use with an external usb charger to have another 220V batt charger
Cons: In some usb ports (front ones in computers) the charger is a little bit big so it can not fit. Just use the back ports
Other Thoughts: The device for changing AA to AAA batteries (change of size for the contacts) is not very intuitive