Lets get down straight to business.
Flipkart is a good ecommerce website.
MOST products are original.BUT always remeber to check the review and rating of the seller from whom you are buying the product. higher the rating of seller with positive reviews the better .dont prefer buying from seller who have extremely low reviews or low reviews with bad ratings. Never be careless .
Shippment is fast and reliable for most cases
Flipkart refund/replace policy is good .works almost instantly . I have refunded two products from flipkart sucessfully within one day of them being delivered back to seller.
All And all a good ecommerce website which can be trusted with bit of alertness as none can be too sure. follow what I have mentioned above and I can assure you will minimise your chances of being cheated here.