Their 3G data charges are atrocious. They charged Rs 5700 for 19 MB usage...worse, they refuse to explain, why this is so. Do not ever switch on 3G. Stick to 2G for data. Leave them if you can. I would recommend Docomo as they are quite transparent.
However, their coverage is poor as they are running three different services, on the same GSM network - Virgin, Docomo, Indicom. Plus their customer service is more bureaucratic.