I purchased the matress because my grandson was allergic to dust mites and the memory foam matress is dust mite resistant. The price of the matress was less than that of a good quality conventional matress.I let it set for 24 hours to allow it to attain its original shape. They direct you to let it set out for 48 hours. You can, however, sleep on it during the period, but it will not reach its full comfort potential until it has fully expanded.When I asked him if he liked the matress he said it was no different than his other matress. I guess it was not yet fully expanded because two weeks later he told my wife it was the most comfortable matress he ever slept on.He has not been coughing as much, so the dust mite resistance feature must be true.I gave it a 4 star overall rating because it was not as comfortable as my tempurpedic matress, but it was only one eighth the price.I will be buying another to replace the matress in our guest room.Definately a great deal for a little over $300.