A
futon is an essential piece of
furniture because it is so
dynamic and flexible. It is good to lounge on and to just
kick back. Then you can have a
friend sleep over with minimal
adjustment of other house furniture.
(Hint: Try putting a thick velvet blanket on the futon as an under blanket...absolute heaven)
On the contrary, futons are somewhat hazardous to your health. They do not support good posture whatsoever! Any way that you try to sit in them, you either lounge (with your back as crooked as a question mark) OR sit completely upright and be uncomfortable as hell. Take you pick...spinal damage or unpleasantness.
Simple solution: When your futon is in the upright position, try putting a pillow behind the small of your back. Thus, straightening your back and preventing discomfort.