Flipkart is now my official go-to bookstore. They have been very prompt in delivering the books and the packaging is also very nice. I do think that they should offer special discounts to regular buyers, start some sort of loyalty program.
What can also improve is the reviews for a book. Customers should be rewarded for their reviews with some point system which they could redeem on future purchases or just have a badge system of sorts.
I would highly recommend this site for book lovers. It saves you a lot of time (and hence money too!)