Thanks for your feedback.
1. 'it only comes in white and my S4 is black'
Blue color will be available in due course. Please see http://www.amazon.co.uk/gp/customer-media/product-gallery/B00EZC6QK2/ref=cm_ciu_pdp_images_dav.
2. 'Battery Life seems to be good so far'
Compared with other battery case for S4, we manage to keep Samsung original 2600mAh battery in this power case. Thus, along with extended backup 2600mAh battery case, this power case is able to provide genuine 5200mAh to let your S4 go around for a couple of days.
3. 'takes about 5 hours to charge'
Bellow is formula assisting you to calculate charging time.
((Battery capacity/charge rate current)*11/10)= charging time ( 10% energy loss during charging)
For example, use 5V/1000mA Samsung original wall charger to charge power case, suppose 10% energy loss.
(5200/1000)*11/10= 5.72 hours.
It has been approved this battery case is able to provide genuine 5200mAh capacity. However, if you want to charge at fast speed, you would better choose 5V/Max 2000mAh wall charger.
At last, we do have wireless charging battery case for S4 available in our amazon store. Please search 'KiwiBird wireless charing case'
Should you have any queries, please feel free to contact us via KiwiBird_direct@outlook.com or reach our customer support at 07717 688088