I've used indoor antennas years ago when my outdoor antenna collapsed. One simple comment- bad. The reception is fairly poor and the antenna requires relocation everytime I change the channel. And if you think that PVC trunking is ugly, I personally feel that the indoor antenna is uglier, with a pinch of cheapskate look.
If you don't mind spending a little more money, I will suggest you to hack the walls so that you can put another cable into it, and then get a professional contractor to seal and paint the wall. It's troublesome for once, but neat.
TV Antenna Strike by Lightning, Advice needed on indoor antenna