The network of Airtel is obe of the biggest network in india.It has cover almost every villages nd urban areas too.The network of airtel is very very good.I am also a airtel user since 2006.
There is very good customer service in airtel.Airtel also provides loan facility at any time if u have to make a urgent call.There is always 24* 7 customer care facility.
Charges and billing are also good but it may be get improved .