The main thing for me is that i can use my phone when discharge.
The second thing is that it will even charge the phone, an added bonus.
Form factor is great, thin and longer than a BIC lighter about 1.7 the size of a BIC.
PROS: Works as promised, keeps the load for long time (weeks or months?) I dropped it in my backpack and forgot when i last charged, so long time ago. Then one day at Marineland a friend ran out of battery on his Blackberry, gave him this device and he was back in business again!