I downloaded the new Jio chat application for android and have been using it for the last 3-4 days. There is a good feel to the application and it seems to have been put together by good professional team by the looks of it. I am also of the opinion that when I use Jio chat using wifi from my cable broadband connection the lag is not there atall and I feel as if it is a voice call made over the mobile phone's own network. I also had a chance to speak to someone over the Jio chat application while he was on Reliance 4G trial network in another part of the country and I must say I do like what I experienced.
No lag atall which is mostly associated with all wireless data connections due to large number of hops and some hardware constraints.
Reliance Jio is on to something good I believe. You can download the app from Google play store by typing Jio chat. It also has video feature which is again good quality.