I do not know whether the bb connectivity is good in other areas of Delhi or not?
I can vouch that bb speed in rohni is just horrible. I had two connections for a few years. I have got disconnected one about 6 months back and the other one I am getting it disconnected this month or so i.e after getting the Airtel bb.
We have tried all sources of MTNL to set the problems set right but, it seems to old work culture of MTNL - everyone keeps on passing the problem to the next level up/down suiting to the individuals to end in sight.
I will advise to keep away from MTNL bb in the areas as problematic as rohini pl.
N.K.V.