Happy with the thermostat. Not an easy process to connect the mobile app to it tho. Took an hour and a half on the phone with tech support to get it done.
The installation instructions need to be much more comprehensive. I was installing this to replace an old SPDT thermostat and it took hours of research to figure out the correct wiring configuration. It turned out to be relatively simple and something that could be easily covered in an online guide. Don’t rely on someone having the correct wiring in the previous thermostat!
Purchase the T9 w/1 remote sensor. Fairly easy to install on my 2010 Carrier HVAC which has the "C" wire. The instructions are simple enough but I do recommend reading it completely. Used my iphone with their APP which seems to work well and has not crashed or locked up. The remote sensor (2 AAA battery included) does exhibit long Hysteresis which I feel is good to prevent temperature flapping. It also has IR occupancy sensing that can be turned off. Been in use for about 10 days now, and so far its been reliable and works consistently. For those IT technicals, your WIFI AP must support peer to peer discovery otherwise the Smart phone app will not be able to discover it.