Yeah. Frequent disconnection, high latency, and packet drops. There was a time when speed was the issue. But you know, even if BSNL gives us 100Mbps or more (think of 100Mbps as 10 Lane express highway, where they have the worst kind of routing and traffic flow control) you still reach the destination in the same duration as if you were on 4 lane highway with almost perfect traffic flow(or maybe faster?).
My analogy might be wrong but the routing and latency are big issues.