I'm basically pretty happy with the Indow inserts. It hasn't been long enough to tell if it will be reflected in my electric bill (I have baseboard heat in a 125-year old house) but it appears that it will make a difference. I notice the thermostat is lower, so fingers crossed. Most noticeably, I had terrible condensation on all of the windows in the house in the winter. It appears to be eliminated completely, which makes me very pleased. All in I would, and have, recommended them to my friends.