I’ll be honest upon opening the box and removing the plastic I was not impressed, I left the mattress laying flat (well as flat as I could considering the both ends were curled) as directed and after several hours it didn’t seem to be getting any fuller. It took well over 24 hours for the mattress to start to fill out and still the ends are slightly thinner than the rest of the mattress but I’m actually using it on a daybed for sitting purposes not sleeping so it is fine. I would say that even though there is some memory quality to the mattress it is extremely firm.