Customer service of amazon is good because when I have got few products which have something missing, defective or I don’t like got easily refunded or exchanged.
Product quality depends upon the amount invested in it or simply price of the product because the cheaper the product the low quality will be.But I have some bad experience in mobile printed cases because the quality & picture of the product shown was not as same. So I have to return those phone cases.
Delivery time is around 5 to 7 days without any subscrition which is not too much time.
App & website has a good & easy to understand for new people.
I recommend you that you can make online payment on products of low cost but it is recommended to pay cash on delivery on high value products to be on safer side.