The screen displays current temp in Celsius (no F option) while idle. Push Set, then + or - as the display flashes, to adjust your trigger temp. Push-and-hold Set to enter the "main menu"; where you can adjust settings like Hysteresis, Heating or Cooling mode (defaults to Cool), and other settings I didn't play with. Its crude, and not too user friendly, and included instructions are in Chinese, but I like a challenge. I'm powering it from the same 12v source I was using to power my fans, running the thermostat and fan in parallel essentially off the same PS. For those interested, it can be powered by 9v battery, and it even fired up on the 6v setting on my universal PS. I would also like to figure out how to attach one to run my AC powered cool-mist humidifier as a way to manage temps during the summer/high-heater usage days.
Check out this interesting thermostat upgrade by /u/vahpor.