One of the biggest cons is that above the tv is way too high for most people's optimal/comfortable viewing. There are several different opinions about the best height at which to view a tv, but generally when sitting you should be staring at the center of the screen or at the very highest at the bottom of the tv. Unless you have an unusually low-profile fireplace, watch tv standing or are like 6' 6" tall, a tv mounted above the fireplace is going to make for some uncomfortable viewing.

If they are accent chairs, put them right next to FP! Pull them away when you have fire.

Could you post a picture?

Not wanting to build anything just make this fireplace look nicer and not so much of an eye sore... cheap and DIY as it's a temporary house!