Jio sim is widely used in india, as there are so much users, so some could face internet problem, but trust me when I use I dont face any problem in internet, and calling wise its ok, and its download speed is very good
Coming to its consumer service yes they take time but at the end they will solve your problem, while iam in rajasthan and I get good service from jio, and my internet speed is good enough, coming to the billing I would say its weak.
I will definitely recommend jio