Not very well, I lived in an apartment with one of those in the hallway, had to set up a fan to blow warm air to the living room or bedrooms or it got way too cold on cold nights. (which fortunately, were rare where I lived). It'd definitely be better than nothing in an extended power failure, but forced air heat is more comfortable

It’s a wall furnace in the center of the apartment, I guess it blows via convection, outward on both sides of the wall.

These heaters are super common in California, and some larger homes have multiple of them. I assume they’re not as efficient as more modern solutions, but they are certainly reliable and low-maintenance.