BSNL network is average network in terms of coverage. They also spam you a lot with unwanted messages. They don’t even give you data deduction prompt after you switch off the data.
Their customer care is average, the worst thing about them is that you need to do a special recharge every six months to extend it’s validity to another six months! Some of their data packs are good but others are just like idea or airtel and not cheaper. Their tariffs are also not much cheaper and their network is not consistent in all cities. So overall I would say it is just an average telecom operator and needs a lot of improvement.