BSNL Broadband is one of the best ISP provider. I had taken unlimited plan of 900UL which gives a speed up to 1 MBPS upto 6 GB and thereafter 512 KBPS. It provides a good concept to upgrade your plan in middle of the month after 6 GB(1 MBPS) datas.
You can opt for it or not it depends upon you. 512 KBPS is good for browsing. Download speed touches 120 -130 KBPS in 6 GB datas and thereafter the download speed reduce down to around 60 - 70 kbps which is good for unlimited plans. You got several plans to choose from according to your needs.
Disadvantage regarding BSNL Broadband is it got worst customer care service. If in case of a rain or a thunder shower the Internet is being cut off and if you registered a complaint they take minimum of 4 - 5 days to recover our internet services which is too ridiculous.
This is the only drawbacks according to me but apart from all this I will put my double thumbs up for this ISP.