I have used airtel network, and been using it, this was a very costly network I observed, they charge very high on value added services,
other side data packs are also very costly, unless you invest a minimum of 150 you wont get 1 GB of data, In this same indian market operators like idea, uninor are providing very good offers.
But good about this network is signal maintenance, it works even in villages with no disturbance but they cannot invest an amount of 200 rs per month. Rates has to be reduced.