I have had a similar one and I think it is convinient to have one around the house and car for emergency. No need to worry about batteries.
Hand Crank Self-Powered LED Flashlight, One High Power LED, Black, MY-072
Features:
Hand crank self-powered
4 LED light includes 1 high power LED
One minute cranking could provide 30 minutes lighting
Specifications:
Material: Plastic
LED Totals: 4 LEDs
Battery Type: Build-in lithium battery, 3.6V / 40mA
LED light bright: About 2000 mcd
Dimension: 4.5(L) x 2.2(W) x 2.1(H) in
Main color: Blue and Black
Hand crank. Should be pretty easy to use!