I have been using BSNL 3G services for more than 4 months now, majorly because I do not have a choice in my area. There is just 1 ISP in my area Pimple Nilakh, near Rakshak Society. He claims to be providing Airtel and Sify leased connections but actually bottlenecks / chokes downloads to 30 kb/s using his router. Yes! I know thats like a tortoise running a hares race with todays speeds in the mkt. :)
So if you take even a 1 MBPS connection from him, you will still get a download speed of 30 kb/s though the browsing speed might be higher.
I know folks, you may find it hard to believe that even BSNL landlines do not find it feasible to lay their poles here since they have to cross 1 km of defence land from Rakshak chowk. The same internet service guy gives them a feasibility report saying that its infeasible for BSNL to come here even though there are 200+ houses in the locality.
BSNL 3G coverage was patchy in my area to start with and the download often used to drop within half an hour. I was using BSNLs unlimited 3G plan for around Rs. 1500/-. They had excellent offers until recently when they revised the prices. Now, its Rs. 1500/- for 15 GB which sounds expensive but is still the best deal you will get with current service providers.
The avg download speed is 150 - 200 kb/s and its good enough to download entire 700 MB movies within a few hours or say overnight. Also, after they limited the download plans, the reception has improved and the connection doesnt hang for around 3 - 5 hours at a stretch. Though its not the best service you might get, it is definitely a VFM proposal if you do not have a wired connection or need to travel frequently, yet need a good connection.
The micromax 3.4 mbps card (Rs. 2500/-) that I use is universal and can work with any 3G or 2G SIM (I have used Idea, vodafone and Tata 2G cards). Overall, I would say that the BSNL 3G service is good enough but more importantly, you are getting better bang for your buck than most 3G services if you need to use them.