My rating for this product is at a solid 4.5. The capacity is very close to advertised, but works hard to recharge my Nook Color at 4000mAh@3.7V. The unit is mostly used as a desk charger for my wife's Iphone 4S when at work (teacher), and performs that task perfectly! The build quality is as expected. The functionality and directions are easy to use, and as expected. Recharge time does vary depending on the AC/USB Converter, but the item does get a full charge as expected.