I just Migrated from 2G to 3G and this is my review. I have a post paid connection and the extra charges are 25 Rs per month rental for 3G. The network coverage is not very good and its better to set the phone to dual mode rather than UMTS(3G) mode. If you set the phone to UMTS mode and if the coverage is not there you will not be able to make or receive any calls. At home in Bangalore city sometimes I am not getting 3G coverage.
Video calls can be made to others only f they too have 3G enabled(BSNL) operator and phones. SO right now its useless. When you buy a 3G handset make sure it has a good browser(not opera mini).Its better to pay more and go for a nokia e71, 63, 72 or 5800 rather than go for cheap phones. I am not sure if BSNL has settings for android phones.
If you want to check the speed of 3G on your mobile device go to https://speedtest.in on your phone browser.
Dont expect much help from BSNL helpline. They are pathetic.