I am using Flipkart more than five years and I can said that I trust flipkart very much.
I bought mobiles two times and books. Everytime they delivered the products on time. I purchased mobile and they delivered it to me on the next day itself.
Their mobile platform is good and their website is also good. They give lot of offers and discounts.
About customer service they are responsive and determined. They solve queries as soon as possible.