I also used me to recharge my GPS when hiking or LED torch (with USB port) ... in short an external battery is a must today.
The only complaint I could make regarding the LEDs indicating the remaining charge. I do not find them very readable, especially outside. I prefer to have surprisingly 4 LED which indicates the load rather than the fairly readable bar.
With 2a and 2.4a port, without charging the most demanding problem as i-gadgets (Apple)