This is my first bed in a box I've ever bought! I was a little nervous about the low price and not knowing what to expect, so naturally this has sat in my cart for quite a while. I purchased this mattress to replace my extremely old pillow top that I've had for well over 10 years. We have only slept on this for two nights so far, but OMG I am so impressed with how comfy this bed is!!!-We let it sit for one full day before sleeping on it, but it was pretty much ready to be used as soon as it was unpacked. No weird or chemical smells after opening. It also arrived three days early during the height of Christmas season!-Be careful when you cut the plastic off this mattress. It's vacuum sealed and literally burst open with enough force that it actually pushed me back a bit due to the inner coils! To be fair I probably opened it improperly.-It's definitely a true medium-firm. I HATE super firm mattresses. It is firm enough to provide support and soft enough to be comfy and cozy without sinking. I don't feel like I'm sinking into this mattress at all, and there are no imprints left from me sleeping on it all night. If it were any firmer it would be like laying on a board.-The edges of this bed do sink in more easily than the rest of the bed, which is to be expected considering ALL mattresses lack edge support to differing extents, but not nearly as severely as some of the other reviews had led me to believe. Some have suggested that you can't even sit on the edge of the bed without sliding off, which is honestly just silly. You absolutely can comfortably sit at the edge of the bed without sinking in or sliding off, unless you weigh over 250 pounds or are using this bed with no base. We have this bed on top of our old box spring. My partner and I are both 30, weigh around 180 and have had 0 issues with the edge support so far. I actually sleep very close to the edge of my side, and I don't feel like I'm sinking or sliding at all.-I am an all-sides sleeper, I'm turning in bed all night like a rotisserie chicken. I find any sleeping position equally comfortable on this bed. It doesn't absorb movement to the same extent as a full memory foam mattress, so if you're sharing this bed with another person/doggy/etc you will feel them move, as you would with any other mattress other than full foam.-This mattress does hold onto heat. I run hot at night and I can definitely feel the difference between my old mattress and this one. It's not excessively hot but it's enough to be noticeable.I will update this review should something go horribly wrong but overall I'm really, really happy with this purchase! It has been worth every penny so far, it's an excellent mattress for the low price point and I would absolutely purchase again. I'm so happy to have a comfy bed again. I can't wait to sleep in on this bed on Saturday morning :)