I have been using JioFi 3 for 3 months now and this is what I feel about the product.
If we talk about the looks this product comes in a Rectangular curved body with a small OLED display with Matt body finish. With the Matt body it is very easy to handle and does not slip out.
It has a good battery life. It has a battery of 2600 mAH which is an upgrade from the 2300 mAH battery of JioFi 2.
If you talk about connectivity, It has WiFi 802.11 b/g/n. You have an option to connect upto 31 Wifi devices.
The internet Speed depends on various factors like Network and number of connection, the speed provided by this very good. You can stream HD videos without any problem.
It has an SD card Slot. It micro SIM slot as compared to Full Sim Slot in JioFi 2.
I never had any issue with the product so far so I never had the opportunity to experience their customer support.
One Negative is that they do not give you any charger with this so you have to use your Mobile charger.
All in all its a good replacement for your Wifi Router and You can carry it anywhere in your pocket.