Yaa it depends on Operator / Network.
I was on roaming last month. Coverage was good in Delhi -> Gurgaon - > Jaipur Highway. Stayed in Pilani (Rajasthan) for couple of days, there none of operators gave usable speeds.
Airtel charges 900 something for unlimited. MTNL/BSNL charge 400 - 500 for the same.
am i missing something , gprs cannot theoritically provide speeds above 48 kbps
You are right about gprs, it gives poor speed. But if grs network support EDGE then speed can go up to 300 kbps.
Most of GSM networks support EDGE.