The 4" memory foam mattress topper is very comfortable. It does allow your body to sink into the foam and it also does seem to hold more heat. I sleep much warmer now. If you are looking for something very firm this is not the topper you want. Another thing to consider is the extra thickness added to your mattress. I have deep pocket sheets because my mattress is a pillow top. With the extra 4 inches my sheets will not fit over the topper and mattress without being secured with something. Overall this topper is what I expected because I had researched my options. I am pleased with my purchase.