Have been using Spectranet for last 3 years. Had to leave their service in between as they they increased the charges exorbitantly without informing. Then again they came out with 3 months advance rental with 24 gb in a month. The speed is quite good and there are hardly any issues.
All in all a good one when compared to Tata docomo(which is really bad) and Bharti Airtel which is little expensive.