Amazon.in is good website for online shopping. Not only amazon.in but also amazon.com is also good. Its customer Service is good. Its Product Quality is EXCELLENT. Its Delivery Time is also Quite GOOD. The only Disadvantage that I have found is that it sends our PREPAID products through POST which is not good because employees in the Post are PRETTY CARELESS. But rather than that the Website is good and I have no idea about its app as I have never used it.
But I can easily say that Amazon.in is an reliable Website up to some extent. So I would prefer to Do shopping through it.