TATA DOCOMO is attractive operator nowadays giving rates for calling and internet are very cheap as compate to other operators .i would suggest you to get join with DOCOMO if you have good network range in your are.
One of the limitation point of this operator is network range because so many places are not covered bt it and its growing day by day and it can get more customers .
Nowadays its making more customer because they give choice to customers by providing CDMA service and people who are disappointed with reliance as reliance CDMA is closed now so they can come to DOCOMO CDMA it has also great plan and service of CDMA network.