There are several issues and disadvantages with a memory foam mattress. The first issue is regarding its smell. It is true especially with the new memory foam mattress that comes fresh from the bag. But the smell usually dissipates in several days or weeks and simply airing it out speed up the process. And in some cases, costumers who are extremely sensitive to smells require change of the mattress. And since the memory foam us made up of polyurethane product, it can be flammable. And because of this, concerns have been raised that a high level of fire retardants are usually used in memory foam. Another issue is that, memory foam is too firm but the one you tried is the showroom is not that firm. Well, this is because that the memory foam breaks in during a period of time and the foam in the display room have been through that process making it less firmer and more comfortable. Eventually, the one you purchased soften too in a period of time. Another problem is that memory foam sleeps warmer, fortunately this issue has been resolved by many manufacturers. Many companies have designed breathable covers that permit air to circulate between the body and the foam. Some companies even have breathable foams. Breathable cotton sheets over memory foams have proven to improve heat issues. And the number one issue that prevents some buyers to purchase memory foam is its high cost. But remember that despite its high price, the mattresses are usually of higher quality.