Used in the African desert during winter, it kept an Iphone and 7.2v(1000mA) Camera battery working without problem.
Hard to get hold of in the UK depending on the season, decided to go for the 13watt version to get full 12v, 1A capacity. Even this struggled to charge my existing Tekkeon (they are great) battery - so consider the matched Goalzero battery if you wish to use gadgets in the day and charge at night. However that battery is expensive.
I found you do need a battery store if you want to keep an Ipad topped up as they need >1A. Obviously 13W/5V does suggest 2A is possible, but in practice didnt work. However a battery can charge up in the day, and spew out more Amps (>1A) at 5v when you need it.
Another traveller used a 7W panel matched with the 4x1.5v battery charger option and this sufficed to keep a 3.6v point and shoot well charged.
BTW If you are planning to use it in the UK, it works, but takes much longer as clouds make a big difference.
Appears to work well whilst the UK summer was here! Charged a Powerchimp4a without any problems. Will not charge an Iphone 5 when connected directly to USB connection as the output fluctuates dependant on sun intensity and cloud cover and hence gives the bloody "Charging is not supported with this accessory" error message. Iphone 5 charges from the Powerchimp4a no problems though! Will need to test more thoroughly next year when the camping season starts again.