Used it first night it was received. Almost no smell at all. It took a couple of hours for the foam to extend to its normal size. Huge difference in sleeping experience. Been sleeping very well ever since. This is great for those people who are looking for that "sinking" feeling. Look somewhere else if you like firm top. Size and the cover that comes with it fits perfectly on my king size bed. All I have to say is that I wish I had bought is sooner!