Took a couple of tries to get connected to wifi, but since then it's been stable. Hard to see screen and the touchscreen buttons are too small and easily mistaken for other buttons. But otherwise the small size and bright backlight are very nice. The online control app is fast and responsive. I just would like to have more features like a run time graph, or temperature over time graph, so i can manually optimize when the furnace/chiller kicks on
My only observation that brings the score to "4" is no Humidity Sensor in the thermostat. The people installing the A/C system and Thermostat did not know it was WiFi compatible.