I love the thermostat! It was very tricky to set up because I have an iPhone. But follow the steps correctly and it’ll connect with no problem. I love the convenience of modifying my thermostat from my phone.
Overall, I am very satisfied with the T6 Wi-Fi Thermostat. I found them easy to set-up on the Wifi and generally very easy to use both via the app and also using the touch screen. The only additional feature that I wish these had was being able to do a partial lock on the touch screens and adding a temperature control range to that partial lock. Our T6 Wi-Fi Thermostats are used in a rental house, and we miss being able to put a range that tenants can adjust the temperature to.
This was an upgrade included with my new central AC and Heat and it is working flawlessly. It is a Pro Device that requires a Honeywell Trained Professional to install and initially configure it so not really intended for a novice or home user to initialize. Many folks giving negative reviews likely installed it themselves or used a "Semi-Pro" without the training to do the job properly. You do need to understand the functions and options too such as Adaptive Recovery which you can turn on if you want the thermostat to learn how long it takes to get you home from your sleep or away temperatures to your awake and at home temperatures and then adapt to have your home at those temperatures by the set time instead of having you wait for the system to play catch-up. If you don't want that then you can turn it off which is clearly explained in the consumers user booklet.
My installer disabled Automatic Changeover from AC to Heat however a Free Chat Session with Honeywell/Resideo walked me through the Service Technicians Menu to make that option available. Great scheduling options, automatically pushed out firmware/software updates, option to have a GeoFence to automatically set the thermostat to your away temperature when your not home (which is great for those who's schedule varies), 6 pages of configurable options listed in the tech manual to customize it make for a great thermostat that can be configured for just about any need. With that high level of customization you do need someone well versed in how to set up those options correctly.
You do need compatible security on your 2.4 g WiFi and a current operating system on your mobile device in order for all the features to work correctly however its not reasonable to expect them to support all features on all legacy devices especially those with obsolete technology/security.