I have been using BSNL prepaid service since 14 years( different telecom zones with different nos) .
I never feel like cheated( which is there with other operators like airtel) some times there may be some issue regarding network but what I found overall good.
Regarding plans they have clearly mentioned while I have very bad experience with other operators( they generally put something's hidden) .
I get signals at most of the places while travelling.
Thumbs up for bsnl.