I have been using Paytm for about an year hand it is a nice site. It was the first one of its kind which I came across.and I was truly impressed coz it saved me from the pain of going to the local service provider for every recharge. Also initially it offeref attractive discounts.
Paytm is best only as a recharge app , my shopping experience with paytm was horrible ; I ordered a pair of jeans quite attractively priced but to my surprise I received a horrible pair not worth the price I paid.
So overall paytm is a nice app for recharges but not for shopping.