I have been using reliance GSM prepaid for the past few months now. Reliance is one of the most widely used mobile network in India. Till now it was a good experience as I dont find any problem with the service and network as well.
Reliance allows offering full talk time for particular number as well. The schemes in reliance has attracted me and call rates are cheaper Local / STD calls at 25p / min with basic internet free and if you want more also can able to recharge for 3G data now. They also will be offering 4G soon as it is very useful.