You dont get its signals most of the times in northen part of India yet. It has towers i. Most of the places but it doesnt have every place covered. It mostly uses aircel in these areas to get signal so you need to pay more in those areas and the net speed is not we are used to in other sim carriers.
If you are a data user then it give you very high quantity of data for a lesser cost when compared to other costly carriers but the speed is indeed not that great as we ought to expect. While travelling roaming charges are very high.