I have been using Flipkart for the past one year and I am very much impressed with their service.Initially the products were cheap but now on comparing the product prices to other website I found them to be costly.Their delivery system is quick and also the replacement takes around 2 days to occur which is manageable.
The only product with which I was unsatisfied was the nexus 6 that I bought from Flipkart.It had screen burn issues but when requested for replacement they were able to provide me with Flipkart cash in return rather than replacing the device.I rather find amazon more reliable in this aspect.