In simple words its just awesome.use it as much as you can.
I am using jio sim from oct-2016 for free it gives me internet speed of 20-25mbps if you dont belive then you can check photos I have uploaded screeshot of my speed test.
it also provides free calls and sms
it is free till 31st march 2017 and after that also it is very cheap compare to other companies like 4g plan starting from 150₹ for month with free call and sms.