We bought this mattress back in September of 2013. We use it on a flat wooden-slat platform bed frame. At first, we loved the mattress and thought it was extremely comfortable - not too hard, not too soft. Then over the winter, we began to notice that the support within the foam was giving away completely. My wife is about 5'2 and 120 lbs, I am 5'11 and about 190 lbs. Now in March of 2014, we cannot sleep on it because it is so soft and has no support whatsoever. I can only guess that it must be due to the poor substandard quality of the foam used. We are throwing this mattress in the trash and buying a different brand (a 12 inch memory foam with gel foam layer) with a more firm (dense) foam structure. It's a shame, because the mattress looks like new but cannot be used by anyone needing a reasonable amount of back support. Caveat Emptor - you generally get what you pay for.