We had it done on our house about 10 years ago, so details are fuzzy. One of the main reasons we did it was the entry has a 2 story window/door with full afternoon sun. That room was at least 5 degrees warmer than the rest of the house. And it happened to be where the thermostat was so controlling temps was a challenge!
Because of the size of that window, we weren't about to attempt self install. We just used what the installer recommended, which I think was a 3M product. We're really happy with the results. I've used a 3M product on one of my cars, too, and it also works well.
