BSNL is an one of the old telecom operator of india with highest amount of 2g network tower availbility. But at present time it is wrost operetor in india, with too many call drops, because of backward in technology. 3g speed is good but not enough.
But they are offering too much low cost plan fir roaming and internet but what you can do with data plan if operator does not offer better service.
So pls try to avoid the use of BSNL.