One way Roaming charges, effectively Costly though because of changed landline rates.
One of the best thing is that making it available nearly all the places and can facilitate the roaming thru out india.
Trustworthy as its BSNL will not run or shut the service as airtel etc... in many places.
Problems may be later not yet known but for sure it will be good in terms of network as most widely spread network in india .
Customer Care may not be good, after all a government organisation and it is all about bereaucracy.