I have been using Airtel Sim for couple of years and would say they are pretty decent mobile operator.
Likes-
Service is quick the very next day I bought simcard it got activation verification and all.Pretty good network in all places in Mumbai and don’t experience any fluctuations in network.
The call rates are pretty decent and normal.Customer services are good and service centers are available all over, so comfortable to use.
Dislikes-
Sometimes some services get activated automatically which is annoying and on deduction of balance they don’t refund it.
Data plan rate are bit high and they don’t give any notification or message when our allowed usage limit is crossed and balanced gets deducts which is really disgusting.
And Roaming charges are high.
But overall good network provider with decent range throughout Mumbai.