We've shot lots of INDOOR stuff with our P3P but . . . it was all shot holding the aircraft (motors not running). Not nearly as "Cool" as indoor aerials but what I've learned is indoor flying brings new hazards AND new levels of turbulent air. The aircraft isn't nearly as smooth and steady as outdoors and any movements are amplified on video. Remember you probably won't have GPS signal so you'll be "flying the aircraft" and you'll be dealing with swirling nasty air coming from the aircraft from all directions.
We shoot Realtor videos and sometimes they want the appearance of "flying" in the front door and into living space. We accomplish this by holding the aircraft and walking it as if it were flying. It's turned out nice and they've been happy.
Indoor + people = bad Drone publicity
*Edit - Added comment below*
The Phantom puts off a LOT more wind than you realize and inside it's magnified and will blow stuff around more than you would think.... napkins, pictures, curtains, balloons, posters, signs, cups.... EVERYWHERE! Also if you get close to a wall or large structure the air will go DOWN from the aircraft but hit the wall and go UP and back into the aircraft (recirculating the air) so if you happen to kick up dust/dirt/trash/napkins be mindful as they could get pulled into the props in the blink of an eye.....