Please never give it a try. Customer service is pathetic. They lure customers through extra cashback which they never give. My personal experience is that they have Rs 75 extra cashback pending from two offers( Rs 25+ Rs 50) which were scheduled to arrive within 7 days of transaction but I have not received that even after 15 days of one and 8 days of another transaction.
I have done lot of transactions with Pennyful but now not in mood of doing a single more.
I suggest you to use other cashback sites such as Gopaisa(which give more cashback but charge Rs99 for every 1000 transactioned) or Flippaisa rather than Pennyful.