I have newly subscribed to Idea Prepaid. It has good coverage over highways in Maharastra and also city coverage is increasing. It is good than my previous network operator(BPL) in all aspects.The indoor signal strength is quite good and with amazing voice clarity and talking about coverage I am able to recieve signal at a place which is somewhat away from the city limits near Pune and also in smaller towns. I have no problems with Idea atleast in Maharastra.Their customer service is also prompt and good.
Idea is steadily and rapidly increasing its quality in terms of Coverage and Signal strength and they are having currently around 600 plus cell sites and 100 more will be added within a month in Maharastra and Goa and already new switching center has been added in Pune recently which takes the tally over 5 switching centers in Maharastra.
The only cons is that it gives less talk time as compared to other operators like BPL and Airtel but considering the services given then this is fair enough because any way one needs to stay connected always and in this case Idea is the best option atleast in Maharastra and Goa where it has no problems.