Heh, very much a matter of opinion. Depends on the scale/size of the room, I guess. You'll note that the example photos tend to be in huge, high-ceiled, furniture-free rooms.
Have encountered dangly fireplaces a couple of times in summer holiday lets, so they remained unused, but I reckon a) they must be a complete bastard to keep clean, and b) if you've got a child under the age of around four then you must live in constant fear of them barbecuing their hands on the metal.
I've got a great space-saving idea for a fireplace: build it into a wall. It'll never catch on, I guess...