I am using Airtel 4G LTE since the 4G services are started In India. I will tell the pros and cons of Airtel
Pros: - Basically I think their are not much pros because the facility they are giving are given by other operators too sometimes in low prices than Airtel but thats an other issue.
2- BY using airtel thanks app on doing recharge some times you get data coupons which are reward on offer.
3: -No call related problems
Cons: -
1: Network Issue
Well no strange it dosnt have good network
2 price of recharges
3 network speed is worst than others
4 no customer care support
5: - if you want to chat with coustomer care while calling you should have atleast 20 min 5min starting with ads of airtel
10 min in searching the option
5 min of waiting to recieve call
6: - Fun fact is if you have problem with Internet like internet not working they will suggest you to go through airtel app which works on Internet.