I hadn't heard of these before.
And the more I look at the picture ..... firstly the length of the berth looks too short to be usable. And secondly, if you extend the geometry and imagine the two berths down in the horizontal position there doesn't seem to be the space left between them to put the ladder up for access (bearing in mind that pax are not as agile as freighter crews going up a rope ladder! ).
Lastly, what would happen if the aircraft got into turbulence ? An aircraft is not like a train (where this concept was standard) and will adopt significant bank angles that pax have to be restrained against.