Well, I didn't have any net at home about a year back and I used to go to cyber cafes which charged essentially as much as a dial up costs. They still do that.
The point is the only internet available in india even a year or two back was either at around Rs. 20 /hr which was exorbitant if you added up the daily usage, or around Rs 1000 - Rs 1500 / month, which was out of the reach of a lot of people too.
I agree, and I couldn't do anything else, that Sify doesn't give what it promises, that is unlimited internet. However I believe that getting a month's worth of it for around Rs. 600 is a great leap, from what you'd have to pay to get any internet just some time ago.
Also looking at the past, it's Ok to have internet at Rs. 600 - 700 with some strings attached, I think, as long as it's properly managed and duly conveyed to us.