I am using Phone Pe app from the launch of this app. The user interface of this app is very attractive and I think this is the first app to use UPI technology. UPI means Unified Payment Interface and is quite nice as it transfer bank to bank with no charge, no wallet or so. It also has its payment gateways on several shopping website and is quite time efficient, as I don't need to enter the Card Number and all, just the phone number or upi address, which I like the most. You also get serveral offer via cashback.
One con of this app is that I cannot transfer the cashback to my bank, it stays in the wallet which is not transferable. Give this app a try as it is free.