The LCD displays the temperature in Fahrenheit and Celsius and adjusts the color of the backlight depending on the reading. An ideal range is set at 61F to 67F. If the temperature is in this range the backlight will change green. Above this range and the color will change red, below the range it will change blue.
The great thing about these kinds of displays is that you can immediately get some rough information from across the room.
This is just a quick project. An obvious improvement is to have more variations in color depending on how far you are from your ideal range. I.e. as the temperature increases out of the ideal range, move along the color wheel and use shades of yellow, then orange before hitting red. There’s also a lot of empty room on that LCD. Possibly room for data from other sensors, or maybe just a larger (2-line) font.
Here’s a short video showing it in action (sorry, it’s a little hard to read the display in this video):