I purchased the Pebble so that I could replenish the battery on my Samsung Galaxy S2 and Nintendo DS Lite whilst at work.
My initial excitement at receiving the Pebble was slightly curtailed when I realised that the spring-loaded connection lead was faulty. As a result, I could not charge the unit via the PC, since the lead doubles as a USB input for charging the Pebble and output for powering your device(s)! However, help was at hand - I managed to charge the Pebble using an old Nokia phone charger (ACP-8X), which has a 5.5V, 500mA output, more than suitable for the task.
The Pebble, fully charged was then unleashed on my flattened S2, which was fully charged in about the same time as it would take my AC charger. I just used the standard USB lead supplied with the phone to charge from the Pebble. When the Pebble was plugged into the S2, the message on my phone was that I had it on AC power. That obviously wasn't true, since it's a DC input but the effect on the Pebble is the same as plugging in the AC charger. Since I didn't have a fully functioning unit, I had to sort out a return/replacement. This was done following Amazon's return process, which was very easy to follow and complete. The whole replacement cycle took three working days to complete and now that I've had a chance to use teh Pebble properly, I'm delighted with the results.
My only negative comment is regarding the connection. I still feel there's a weak link with the spring-loaded lead. It is subjected to a lot of physical contact, with the potential for overbending/over-stretching the cables and loosening of the adapter with the various heads. The Pebble itself is superb and I'm so glad I have it, to give me peace of mind that I'm not going to run out of juice when I need it most -> at the end of the day!