It has worked excellent so far but hot weather has not come in yet. For a week or so that we had warm weather, I didn't notice any change in my electricity usage. One improvement can be made in schedule. When the schedule is programmed, even though I turn off the unit,but comes on at the time it's set to turn on after a period of off schedule. It does this even though the temperature is much cooler than requiring AC.
It was easy to install but the plastic window cover is not long enough for the height of my window, which is standard height.