I own one. (yes, couldn't resist.) It really is as loud as you think. It's actually painful to the ears. I've even considered those commercial sound shells they use for the blenders at Smoothie King; even offering to buy one of theirs.
It's not only loud, but it sounds awful. The bearing for the blade/spline drive in the container is really loose and makes violent sound. It feels like the thing is going to explode when you use it.