Me in Poona and using DataOne on Huawei modem (outright purchase) since quite sometime. After dial-up, had gone in for Hathway unlimited connection. In a nutshell, it was one of the most horrible experiences of my life. Got rid of it in a month and got DataOne. Compared to Hathway, it was too good to be true!! Almost zero downtime and most of the time the speed is what is promised (256 kbps). There are times however when the speed does drop to some extent (usually in the day). Customer service is typically BSNL - Horrible! For example, you wont even be able to get POP3 account settings out of them without quite a bit of effort and shuttling pillar to post! But once you are set, you should hardly need customer service... but if for some reason you do, then.... good luck!!
So to answer your question, yes it has been quite reliable. As for equipment, you'd need only an ADSL modem, a splitter and wires. Just remember not to connect ANYTHING before the splitter.