My husband and I are tall, large people. Together, we need a good firm mattress that can last. But we can't afford the bed we really want. Both of us have had many traumatic injuries including ruptured and bulging discs in the back, double torn knees, a torn shoulder, etc. At the time of originally writing this review, I am currently healing from double knee surgery and can find comfort sleeping despite having to keep still with my legs elevated. Let me assure you; This is the BEST sleeping purchase for back problems, joint problems (such as arthritis) or even over sensitive nervous system response problems that cause head to toe pain sensations. While it is not exactly the same as a high quality solid memory foam bed, it is a close competitor and MUCH more affordable! We have had two of these 4" Serta toppers and won't own a bed with out one. Our first was a queen traditional mattress (we always buy the Cali King topper and cut to fit) that was old and not supportive enough. Using this topper provided my husband relief after his first lower back injury and allowed me to sleep through the night without the joint discomfort I was used to. After that mattress saw its end, we bought a very firm (max coil) traditional king mattress set. This topper has made our bed heaven! We are truly spoiled. You will not regret this purchase! I personally promise! Bottom Line: This is high quality, high density, Visco elastic memory foam in a solid piece. It is VERY heavy in weight (you will need help positioning it) and it is critical that you follow the instructions (more info below on that). But it does retain heat. Invest in a good mattress pad to help with this issue. Some additional need to knows: The foam WILL have an odor at first. It is not over powering and eventually "airs out". This is normal because it is 100% synthetic. Keep that in mind when purchasing but don't let it hinder you because the odor does not last and many over react (my son and I have serious allergies & respiratory problems and it hasn't bothered us a bit). Also, if you do not follow the instructions for opening when new, it will fail and be your fault. The material has a true MEMORY . It is critical that you let it unroll on its own and are gentle when placing it on the bed. NEVER force it open or force it to bounce back, say when you are trying to make your bed immediately after getting up. It can lose its memory permanently. Because this product responds to temperature, the corners that never feel body heat will eventually get dark and possibly feel "crusty". This is after YEARS of use and due to being in a controlled environment. If you keep your house upwards of 80 degrees this will never be an issue but if you're like us and use your A/C lower than 70 degrees you will have some discoloration. It does NOT affect product performance overall. We kept our queen topper for 5 years and when we gave the topper to my sister for her guest bed, it was still like new aside from the very corners. Due to the temperature response you will get warmer than normal. It is NORMAL for ALL solid memory foam toppers or mattresses! The name brand designer therapeutic beds do the SAME thing (unless using the new "cooling gel" formulas to help which have holes to vent and aren't solid). The best way to get comfortable if you're hot at night is to buy a high quality "cooling" style mattress pad cover. For both our queen and king we purchased a deep pocket temperature controlling cover from Great Offer Stock. This helped massively although it can slightly affect how much the foam 'responds' to your body... not significant though. Using all cotton sheets will additionally help with heat issues. Your body temperature gets momentarily trapped in the foam and causes you to feel warmer, this is how the product knows to shape to your body. Trapping heat means the product is doing its job. In my book it is not an issue because I'll take a good nights rest with a higher electric bill (for keeping A/C lower) over waking up in pain and never sleeping well. In the end, it depends on what quality sleep is worth to you personally. Finding sheets may be an issue if your mattress was 16+" to start. It was a challenge for us. We found a department store that carried REAL 22" extra deep pocket Supima sheets. But they are pricey. They sell some here as well but haven't found any that are the quality cotton of the department store. UPDATE: We learned the hard way that moving every year will compromise this topper tremendously. There is no way to move it without tugging a little here and there and it eventually leads to small tears. We had to trash this topper after 4 years. One side completely lost its ability to bounce back and became a quick sand pit. We have ordered a thin latex topper and a 2" 4 lb memory foam topper to try as opposed to buying a new king bed. We are also hoping that lowering out bed 1 inch will make it easier to find sheets. I'm not a fan of spending nearly two hundred dollars every 3 years for well fitting soft sheets. Still love true high density memory foam for aches and pains. But there are some draw backs. Hope this review helps!