AirTel has become a part of my family.Every member of my famliy uses an AirTel sim card and they( and also including me) have never found any issues with it.
Some say that their tariffs are a bit costly than others but I dont think so.Their customer service always responds to our queries and also always explain things in a simplified manner.
In the recent Chennai floods, its obvious that the cellular signals will be lost.But as soon as everything came to normalcy, AirTel started to continue their service whereas many of the other service providers were not responding and continued only after a long span of days.
Also AirTel is the first to introduce 4g in Chennai, and my friends were saying that the connection is very stable and is also fast enough.But I have noticed sometimes that the 3G signal is not that strong and because of this the speed drops out.I hope that AirTel will soon clear out this issue.
But overall AirTel is a good service provider and I would love to continue their service.