The network coverage in airtel is good but the way they charge is really worst. Simply they will activate some plan and deduct the currency. I was using 2g sim card and they deducted 60 rs and they activated 3g gprs with out informing and I can say this is the worst way of making money. So only I decided to port to vodafone.
I hope this will not be the case with vodafone and the customer support in airtel also very bad. It takes so much time to connect they simply keep repeating the pre-recorded advertisements