I stay in Delhi and few years back when I came here my first choice was Mtnl sim. It is a government company so its motive is to provide service more than to make just profit and it has a pretty good network in Delhi as well as good internet speed . In my home every one has one Mtnl sim.and one other sim . Mtnl has the cheapest tarrif , it is the only operator which gives ?100 talktime on recharge of ?100 so we get 100% of our money .It has the cheapest 3g plan of a day thats is 40mb @ ?4 .Other tariffs of talktime and internet is very good and much less than other operator Mtnl has made roaming free so I dont have to think about any roaming pack when I go out of station .Also it can be easily recharged through aishwaryasingh23tm freecharge mobiwik or any other app.
One thing is that its network connectivity is not so great but it is okay .Also mtnl does not offer 4g till now .
Mtnl does not have any USSD service to activate any minute pack or sms pack or internet pack from the sim balance , we have to either go to the shop to recharge or use any app online .
Otherwise its a good sim.