Since past few days I am using BSNL's new EVDO service. As its a USB modem, it does not require separate power supply and its highly portable. Also, you get nice download speed if you are nearer to the evdo tower.
But, you get private IP address and all ports are blocked by BSNL. Therefore torrent download is really slow(It requires a port forwarded on NAT/gateway to accept incoming connections).
To solve this problem, you can use third party torrent downloader like ImageShack. It will download a torrent for you. The torrent file can be uploaded to it or an url can be specified. Later you can save it on your local machine using normal http download. It has disk space and bandwidth limitation per month.
Other option is to use Torrent Relay. I have not tried this option, let me know your experience about this service.