I was too busy being deafened by Frank Sinatra a split second after the rotor noise played to even remember hearing the rotor noise; rather than faking the silence they just over-wrote my memory of it in the advertisement with shock-and-awe style Sinatra -- I guess that's okay.
I was positively surprised, despite the music. Some time ago I was very annoyed by all these "drone projects" on kickstarter or concept artist sites about drones following you all day as personal assistants, for example. IMHO, drone noise is just as limiting factor as the battery life and products should have it on their promotion materials, even if it is for a split second.
But while you're doing whatever it is that you're capturing, whether or not there is a loud humming noise the entire time can completely change the dynamic, especially if other people are around.