I had very bad experience with Tata Docomo Photon 3G. Client will not receive any bill for the purchase he/she has made. So device charges are not accounted. On top of that, if you are cancelling your connection, Docomo asks you to pay penalty fee for cancelling the number.
I was migrated to high end plan without any notice. There is a lack of transparency in all the transactions from Docomo side.
Please be careful if you are opting for Tata Docomo Service.