I have owned memory foam mattress toppers before, and they always seemed hot, sticky and clammy. They did not manage moisture like a good mattress should. The addition of a very thick poly fill mattress pad solves that problem. I added the system to an overly firm mattress, and it resulted in a well supported but still cushiony soft sleep. I had zero problems with odor. It did not need to air out before being used. It shipped quickly too...just a couple of days.