If you lose power often or for long periods of time,and live in a rural area where it might be days until power gets restored--then a whole house generator is a worthwhile investment..especially when you consider the cost of frozen pipes,spoiled food,and no heat ,etc..
I have the misfortune of having a recently installed sewer pumping station right across the street from my house,the town decided to build several of these instead of a larger underground facility--it has a big Kohler generator and they installed a huge underground propane tank to run it off of,I'd guess 500 gallons--that thing starts up every tuesday at 1 pm to run for at least 30 minutes,to "test" it and charge its battery maybe (and roast any mice that may have moved in!)--last Friday when a tree hit a pole right next to that building and the power cables melted,we lost power,and that generator fired up --and ran non-stop until the following Thursday..
No one can tell me they are "quiet"--though its not obnoxiously loud,after a day or so of the constant droning,it gets to you--especially at night when your trying to sleep..
its only 100 feet from my house..more aggravating than the noise it made,was the fact it was making 10,000 watts,and I had no heat,no well water,no lights..
Here's picture,you can see it off to the left of the building..