Ive been using Airtel broadband since the time broadband came into existence in my city. I must say that there are ZERO downtimes for this broadband and I am really happy with their services. I get amused with low ratings for airtel sometimes despite the fact that it is one company which has been striving for excellence in customer support and they deliver on time for any issues.
I agree there were issues with airtel initially, but now I have been using it in my home and office and the connectivity just rocks. However, one notable disadvantage of owing airtels broadband is that it does not have a fair usage policy. Or to say has anunfair fair usage policy!. For my internet which has about 50 GB fair usage, after the 50 gb usage, the speed drops to around 512Kbps, which is unfair and has to be atleast 2mbps. Otherwise, I love airtel and I have been recommending friends and will recommend you to go for it.