By my experience, it is really good.
My Father actually uses the device for his purpose. As of now he is in another part of the country.
Whenever I am home, I refrain from using my wi-fi dongle(It is an MTS device).
Reasons:
Horrible services, Slow connection, and absolutely no coverage, and also roaming charges since the circle is UP West.
The first time I used the Airtel 4G hotspot was during my Winter holidays.
Worked really good. Excellent speed. Really good connectivity.
My advice, buy it. And use it wisely. Speed may excite you enough to consume the whole data limit.
Hope this helps!