Product review (5 stars): NOT NOISY if installed correctly.  Terrible instructions, but great hood
Instructions are practically non existent, so here is some advice.  Make sure the ridges on the two half moon flaps are pointing down or else they vibrate loudly on high.  This unit comes with a standard plug, so you will need to have your outlet installed at just the right spot in order to hide it behind the chimney.  The hood is awesome for the price and looks and works great!