I have used both Flipkart and Snapdeal. Flipkart so far is excellent. No issues with any of the order (from electronic to movies to book all are on time).
Snapdeal except for few orders initially, part of which were cancelled (I think the deal they offered was too good for them to honour) .. All the new orders reached me on time. I have used both online payment and CoD.
Infibeam also is good so far, no issue with any of the order, except for one. In that case, they said they don't have any stock, but they failed to inform me even after 7 days. Only after I contacted the CC, he told me so. In any case, I went for an alternate colour option costing the same. So not a big issue so far with any online purchases so far.