I wish I would have found this site last year before I purchased my king mattress set from Mattress Firm. I have been through months of horrible sleep and the worst customer service of my life. I purchased a king Manhatten Reserve set from Mattress firm last July. By January, my husband and I were sleeping in valleys on either side of the bed. The warrenty process was an awful experience. The young Manager at Mattress Firm actually told me that he was going to quit his job because he felt so bad that he had to lie to customers. I filed a complaint with the BBB and the State Attorney General for Texas. I feel like I got taken by a 2 companies that I had thought were reputable---Mattress Firm and Stearns & Foster. I followed the Warrenty process to the letter and was denied any renumeration because the "string" test was not met!!!!! OMG---how can the industry measure indentations with a string when there is no weight on the matress and call this"fair'?
I am trying to "just let go" of this experience and get on with my life. I need to buy a new mattress and I went to a Sleep Number store today to try out their beds. I am so glad that I did not purchase one of their products before reading the comments on this site!!! Thank you to all of you who have posted!!!!! Now, I am narrowing my choice down to the Latex options. I am seriously looking at Flobeds and Sleepez because of the comments I have read here.

we purchased our mattress at Sears. This bed is very firm. We purchased it because my girlfriend likes a firm bed. She complaint that soft bed causes pain in her lower back. i also have pain in the lower back during the night and after gettting out of bed. a hot shower usually helped.
After the very first night, we noticed an indentation where our butts pressed down. we are not heavy people (me-155 she-110). now after two weeks, the indentation is getting bigger. we can only feel it but not yet see it. The bed did solved our back pain problems. however, now my girlfriend is having shoulder problem. we are back/side sleepers. She tried feather bed as a topper. this helped her shoulder some, but her back pain come back. We tried different pillows like down, memory foam. but so far we can not solve the sholder problem. We are going to exchange this bed for something softer soon.

My only update is that this S-Class plush continues to become more comfortable for me over time.

While the Memory Foam in this model is considered a weakness by many, I'm pleased to report that I'm adjusting to it quite nicely. I'm not bothered by it being warm, and our bedroom is seldom at a temperature lower than the high 70's. However, I believe the memory foam does not represent the top layer of padding, so it's isolated from the surface. I'm now beginning to wonder is memory foam actually is a pretty darn good material of construction for a mattress, applied judiciously and properly.

Without a doubt, I like this product better today than I did a few months ago.