Customer Service: Excellent. Amazon provides excellent customer service. Amazon team is always helpful.
Product Quality: Most of time quality is satisfactory but sometime product is not as per requirement. In such cases you can replace or return item in short period of time.
Delivery Time: Timely but in case of late they notifies you.
App & Websites: Better than others like ebay, sanpdeal. Websites needs improvement. Many product description details are missing.
As per me overall Amazon is far better others.