It clicked for me behind a low backed sofa that sat right in the middle of a long room, the back of it facing the entry hall with nothing but air behind it. That stretch of space had been dead for years, a place to drop mail and nothing else, until a narrow table went in at the same height as the sofa back and suddenly the whole room had a spine. A lamp on one end, a stack of books on the other, and the entry finally had somewhere to land before it became the living room proper.
A good one earns its keep through proportion as much as material. You want the top sitting close to the sofa back height, not towering over it, and a depth narrow enough that you can still walk the hallway or doorway behind it without turning sideways. The honest ones are solid wood or a real veneer over a stable core, with joints that are pegged or doweled rather than just glued end grain to end grain, because that's the joint that works loose first under the weight of lamps and books and whatever gets set down in a hurry. Look at the underside if you can. A table built to last has legs that are mortised into an apron, not screwed on through a metal bracket, and a finish that was rubbed in rather than sprayed on thick to hide cheap stock underneath.
Where it goes wrong is scale and placement. Put one against a sofa with a high, rolled back and the table disappears below the sightline, useless for anything but kicking. Put a wide, heavy one behind a sofa in a small apartment and you've built a wall where a walkway used to be. These tables also clash with sofas that already have a console or shelf built into the back, and they fight for attention with anything else narrow and tall nearby, another skinny console, a ladder shelf, a stack of crates doing the same job. One piece doing that work in a room is plenty.
The honest limit is that it only works when there's a back to work with, a sofa pulled away from the wall, floating in the room with open space behind it. Push your sofa flush against a wall, as most of us do in smaller rooms, and the table has nowhere to go and nothing to do. In that case it's just a narrow table pretending to have a purpose, and you're better off without it.
The mistake to avoid is buying one too deep for the gap behind the sofa, so you end up squeezing past it every time you walk through, which turns a useful piece into a reason to curse at your own furniture.