Though I have bought many things (books, cds, dvds, watches, Playstation, clothes) from both flipkart and amazon. Till now I have no issues and got all the discounts and offers as advertised.
The playstation came with an invoice and the three piece warranty card which is generally offered by any SONY product. It is authentic and can be serviced anywhere just like when you purchase from a shop.
I did not buy anything as big as tv (in terms of size) until recently I noticed a very lucrative ad for a micromax. I bought a 40" from flipkart. The TV as well as service of flipkart is very good. Read the details here please.
And I have always received product from both flipkart and amazon well before delivery day (I am Calcutta based).
On the other hand, there are plenty of negative feedback for snap deal. I have very little experience with snapdeal. Sometimes back I ordered few cds available at a better discount than amazon and flipkart. I ordered it through COD fully knowing well about their negative feedback and say 6 out of 10 cds were delivered but long after the delivery date and the rest 4 were canncelled due to some unknown reason.
This is just MY experience. However, every site has its own "horror story" though. Good luck with your purchase.