Nice enough, but it takes up most of the room. I lived for a year in a small town in the south of Japan, without a bed. Instead I slept in a futon - a kind of thick, fold-away quilt that serves as a mattress, straight on the ground. This is what my futon looked like:
This is the same room with the futon folded away, you can see it to the right of the picture. Folded up like this it can serve as a cushion for sitting on, or it can be tidied away into a cupboard. The space it filled is now freed up.
Unlike our massive, awkward mattresses, the futons can be laundered - which must be more hygenic. They are also surprisingly comfortable: not at all cold and only a little more firm than a normal bed and mattress.
They are, in fact, better than beds. Far more convenient, since they free the entire room up once they're folded away. Portable: you can stick one of these in the boot of your car. Hygenic. Light. I imagine they're probably cheaper too.
So why on earth do we continue bothering with beds?
Beds lift the mattress off the ground to avoid drafts (solved with proper insulation and well-fitted doors) and pests (solved with the occasional hoover and/or mouse traps). But for the most part, futons do what beds do, but much better. The Japanese were on to something here.