First unit was faulty. Replacement unit would not work with WiFi even after the installer worked with Honeywell support for 45 minutes. End result - I had the thermostat replaced with a non wifi version.
We had this professionally installed by our HVAC guy. We needed to be able to control the thermostat remotely at our vacation home. The app installed on our phone is very simple to understand making it user friendly. The HVAC technician told us that this particular model won't turn off the HVAC unit if the wi-fi is interrupted by a power outage. So far we are very satisfied with our T-6!