Yes true it is, it's costly, and they are no less than a theif, seriously.
Right now I am charged 80p for 20 sec call.
What on earth am I doing to pay so much.
Though their network is strong, their Internet connectivity is good, but the packages are so high, and you have to pay big bucks for rate cutter too. But the network is quite reachable everywhere.
I wouldn't mind if you go with reliance if your pockets are heavy, but strictly no if you don't have much to pay for phone bills, and the major issue I have faced is, they used to charge me for VAS which perhaps I haven't activated, when enquired they say Vas activated with no valid reason