Here you go, instead of the ceiling - a hammock. What is the point, it is not clear, but very cool. In principle, a hammock is not bad, you can lie around, even sleep, but what, someone likes to sleep in hanging beds.
In general, there are many advantages. Firstly, the room is visually expanding, and secondly, you can save on electricity, lighting the upper room is enough for the lower one. And the sunlight will increase. Thus, you can create at home an additional place to relax. But the main thing, of course, is creativity. There is something extreme in this idea, you can try it if the dimensions allow you to feel like Spider-Man.