This is pretty thin as a mattress (we haven't used it yet as a seat). We have it on a box spring and frame and you can feel the solid surface underneath if you put a knee down on it. However when you lie down and spread out your weight it is surprisingly comfortable. We added a high loft mattress pad (it might be even better directly on carpeting versus on a hard surface). My college age daughter has slept on it a couple of nights now and finds it comfortable (she likes a very firm mattress). I wouldn't recommend it for a mattress someone will sleep on long-term, but as a guest bed it works well. I like that when we are done using it as a bed it can fold into a smaller space go into one of the kids' rooms as a space to study or chair for a friend to hang out. It could easily fit into a closet when folded up (standing on end).