UPDATE APRIL 2024 (1.5 years): Still working fine, still loving it. It’s probably my favorite smart home device, and I got lots of them. So nice not having to drag my lazy…to go and adjust the temperature. Was nice to have when I had actual furnace issues and didn’t have to constantly run up-and-down the steps (though Lord knows I need to) to switch it on/off or adjust the set point- just do it from the app.Can’t believe how cheap it was (purchased used); it’s even cheaper now for a used one. I feel much better having gotten this over a Nest or Wyze or Amazon unit. I get a monthly email report showing usage (in hours).I refuse to get the promo through my utility company for a $50 rebate, because they still have excessively high rates anyway, and then they could have control over my unit.ORIGINAL REVIEW:I bought this several months ago but waited until Christmas Eve to install it. (Not the best time if something goes wrong.) I already have a Honeywell non-Wifi programmable thermostat which has worked relatively well the past few years, and have installed programmable thermostats in other homes over the past 20-plus years. I had purchased a Wyze thermostat also but after seeing so many poor reviews and complaints, I shelved it in favor of a thermostat from an actual thermostat manufacturer.Of course installing those required no rewiring, as they were battery operated and did not require a C-wire. This thermostat, like most other smart wifi-connected thermostats, requires a C-wire to power the unit.Seeing I only have 4 wires with no C-wire, I had wanted to run a new 5-wire thermostat cable to my furnace, to have a C-wire, by connecting the new cable to the existing cable and pulling through the floor/wall. But after having found where the cable goes up from behind the furnace having almost no access, and looking in the wall cavity with a bore scope and seeing that pulling a new cable would likely snag, I finally deemed it as nearly impossible.Luckily the new Honeywell t-stat comes with an addendum of instructions and even a jumper wire to convert the G-wire to a C-wire. What’s nice is that this means Honeywell basically legitimizes what is generally considered to be a “hack”. You move the existing G-wire to the C terminal on both the board and the thermostat - pretty standard procedure.What’s different is that the jumper wire then goes between the G and Y terminals on the control board (even after moving the wire from G to C). I have no idea what the purpose of the jumper between G and Y is; I’ve never seen or heard anyone else mention this. You still lose separate fan control (because nothing is connected to the G terminal at the thermostat).I actually decided to take a tip from electrician videos and used pigtails from the C and Y terminals on the board, as I was not confident the small screws would retain 2 or 3 wires at a time. I basically cut and stripped small lengths of extra thermostat wire, and attached one to the C terminal. Then on the other end I used a small wire nut to combine with the other existing wire(s) which were already going to that terminal. I did the same for the Y terminal. This to me made a cleaner installation, and would be easier to modify in the future should I wish to go back to the old thermostat, or install a C-wire adapter, or even finally have a 5-wire cable routed. It only needs to have the wire nut removed, rather than unscrewing the terminal. (Seemed logical to me after having done this on several electrical outlets and switches. 🤷🏽‍♂️)The unit powered on as expected, and I went through the setup process, which is mainly setting the day & time. I have a plain gas furnace and central air conditioning, and the thermostat was already configured for that. It has many configuration options for different types of HVAC systems; one in particular allows you to have an Auto mode where it can switch between heating and cooling (rather than manually switching as most thermostats do). I tried this for a while but set it back as I saw no value in having it in my climate.To connect the wifi, you change your phone’s wifi to the signal put out by the thermostat. Then you connect to it using the Total Comfort Connect app. You have to create an account, which I did on my PC, but you use the same login credentials in the app. It was fairly straightforward. Even with the phone connected to the 5 GHz signal, it was still able to link the device to the 2.4 GHz signal under the same SSID (I didn’t have to turn off the 5 GHz signal, as some other smart devices require).You can control and program the thermostat either through the app or via the web page. You can change between heating and cooling modes, and also between fan modes (though again, the “On” setting is irrelevant; the thermostat will click but nothing happens).I also managed to link the app with Alexa (which I use more often) and Google Home (which I rarely use), just to try each one. In each the functions seem to be much more limited; in fact in Alexa you can ONLY control the temperature, not the heating/cooling mode. Google Home allows this, but that’s about it.One shocking thing is that I checked my router’s app, and it reported that just in the first hour after installation, the thermostat had used 1.3 GB if data. That seems like a huge amount for something that isn’t a streaming device. It’s not clear what that amount of data was used for.Right now it seems to read the inside temperature 2-3 deg F lower than the digital thermometer I have in the same room. This is weird because the previous Honeywell thermostat used to read the same temperature.UPDATE MARCH 2022: Meh, still ok but not game-changing or disruptive tech. I like the convenience of being able to adjust the temperature without going to the thermostat, but other than that it doesn’t offer much. No substantial energy savings to speak of. I linked the TCC app to Alexa, and it shows an estimate in the Energy Dashboard. I’m not sure if it’s accurate or not because it’s making a guesstimate of the gas usage. Would be nice if I could set a routine in Alexa so that if the temperature reads below/above a certain point, it kicks on the heating/cooling until a desired set point is reached. Actually in Alexa you can’t even change the heat/cool mode; only the temperature.No issues with the wifi disconnecting like others have reported.