Yes, I love that whole house fan!
I have a sliding glass door to the back screen-porch at the opposite end of the house. I open this up and flip on the fan and in about 40 seconds the house temp goes down a significant amount.
It's also very useful when you don't know the previous owner sealed the chimney at the top with a large piece of slate and you decide to start a fire in the fireplace and fill the whole house with smoke.
Don't ask how I know that one, I just do.
It's also very useful when your remodeling your bathroom and have dust and dirt floating in the air. Flip the switch, open a few windows and out goes all the crap.