We spent a lot of money on the "Nora" model and we just loved it for the first few months. Then it just started sinking more and more even with monthly rotating. Now there are 2 trough like others have said. It has to sink an inch and a half before you can call in on the warranty but since it is foam on top it is near impossible . The breakdowen must be taking place under the foam top.

paid alot of money for a matress that you sink in to !! very uncomfortable

We initially purchased the Simmons BR Oceanside, which we found after 30 days of trial that it had too much foam and we sank into the bed. I did not like the sinking feeling and needed more support for my back and stomach sleeping habits. So we exchanged for this bed and it has helped with the back aches. We are lighter weight people, so we stay on top of the mattress as it is firm and supports our weight well. The cushioning is just comfortable enough that if I sleep on my side, stomach or back, I am comfortable. We have only had it for a couple nights, but I have noticed a significant difference between the firmness of this one and our previous choice. If you are looking for a firm support, but some cushioning on the top, I would recommend this mattress.