ORIGINAL REVIEW 2013: I held off on writing this review until my wife and I slept on this bed for one entire year.After toiling for months over which mattress to invest in we decided on this one. First off the mattress was very reasonably priced; the king sized we bought was less expensive than the Sealy innerspring mattress we were replacing (after eleven years) by ~$500. Regardless of the price, this mattress was a great choice. The delivery took several days and came in a vacuum sealed bag. After I brought it up my stairs I placed it on the 7.5” tall box spring (which has 3” support slats) and unwrapped it. I would suggest not breaking the vacuum seal until the mattress is in place because it expands quickly and can be difficult to move once it is expanded. Also be sure that the mattress is facing the right side up. After a few minutes the mattress was at about 90% thickness, after several hours it was fully expanded. We left the window open in our bedroom for the afternoon to let the chemical smell dissipate. When bedtime came the bed was sufficiently aired out and the chemical smell was noticeable only if you really jammed your nose into the mattress. As an aside, my wife and I were prepared to sleep in a spare bedroom if the smell was still too much but we encountered no such problem.Now for the good parts; standard sheet sets fit perfectly on this mattress and laying on the bed was extremely comfortable (analogous to the TempurPedic we tested while buying a different mattress for one of our kids). The memory foam feel is quite different in a good way; supportive but not overly firm. When I was researching memory foam mattresses I got quite confused by the fact that one reviewer would say too firm and the next would say too soft - while referring to the same mattress. After sleeping on the mattress I could rate sleep quality this way: the memory foam becomes very tailored to your body, it feels firm at first but as the foam compresses it supports your body weight in just the right places. The softness feel comes as you sleep on it, it stays soft and comfortable (and at the same time supportive) without feeling like you are sinking into quicksand. It is really great.After sleeping on it for one year and four seasons, I can say that the mattress is still as comfortable as day one. I am a 230lb oaf and my wife is very petite yet we both love the feel of this mattress. There is no warping or hammock-ing of the foam where either of us sleep. Yes, it is a tad warmer in the summer but nothing too drastic.All-in-all this Sleep Innovations mattress is a terrific mattress and an excellent buy. The 12” height is plenty thick and does not make you feel like you have to jump up to get into it like the 14” did. After sleeping on an otherwise high quality spring bed while on vacation, my wife and I both commented on how we could never go back to a non-memory foam mattress again. This was our favorite Amazon purchase EVER and I highly recommend this mattress.Despite my superlatives, keep in mind that what makes a mattress good is a very subjective thing; what is comfortable to me may not be for you - so I attempted to describe this mattress' attributes as best as I could. Hopefully this review helps you decide if it will be a good choice for you. I attached a few pictures for reference.UPDATE 5/1/2015: This bed is still comfortable and it is holding up very well. The foam still compresses and releases as when new and there has been no lumping or hammock-ing. A few months ago I did rotate it 180 degrees to shift the areas that are laid upon as that was recommended to us by other several reviewers (thanks to them!).Still give a full five stars as my wife and I love this bed.UPDATE 11/16/2020: After a bit less than nine years, my side of the bed started to get a little lumpy, presumably from uneven recoiling of the foam after I get up. We loved this bed so much that we ordered an identical one to replace it and the new one seems just as good thus far.