Its been more than 5 years I am using Airtel Broadband services and I must say it is one of the best ISP in the Market.
The best thing I liked about the Airtel is their services, if at all anything went wrong you just dial the customer care no and you will get the immediate solution for your problem, which is one of the key feature for any ISP or any other business. to make the customer happy you have to be good in services.
some people say It is bit costly with comparison to other ISP but I didnt find much difference. its more or less same only.
If we talk about connectivity. its fantastic. If I could recall it properly I think only twice or trice I logged a complaint for any connection issue which is also resolved on times.
So overall I am a Happy customer of Airtel BB.
Thanks!