I wasn't sure what to expect, the reviews on firmness went both ways. So, I'm writing mine just to add to the mix :)
Came a little bit later than expected, but it wasn't a surprise since I got it on the one day sale. Which I've noticed the price for that has popped up again on sale, so it isn't just the one day price.
Box wasn't wrapped, so it wasn't a secret what was in it. Came perfectly fine, no dents or tears. The mattress itself was wrapped tightly in plastic. Pretty amazing really. It sat in my bedroom for a couple of days since I wanted to open and let it air out overnight and I still had my current mattress to be picked up by my son.
Make sure you put the mattress on the foundation you plan to use before you start cutting. This is very important.
Old mattress out. I have an antique Queen size bed frame that uses wooden slats as the foundation, plus I have my old box spring. We placed the Serta on the box spring and started to carefully (be very careful) cut the plastic. It is really amazing that this bed is only about 3 inches tall when still in the vacuumed package. Cut diagonally and do it fairly quickly. The bed starts sucking in air and expands to the full Queen size in literally 2 minutes, maybe less. Aaand, you're done.
It does say 12" and mine has fully expanded to 11 1 /2" . Close enough for me.
First thing I noticed is after coming from a pillow top was how flat it is. Flat, flat. No lumps or comfy spots, just flat. Don't try to do the cute little jump and land on it, it's flat and firm and not a lot of fun.
First few nights I was unsure how I felt. It was firm, but after about 15 minutes I stopped noticing it was firm. Weird. It is because of the memory foam, weight and mixed with body heat, it conforms to your body. I've had it now for about a month. I can definitely tell where I sleep and where I do not. The softer side is where I sleep each night. As time goes on, the memory foam softens. It isn't squishy soft or like it is breaking down, but it does that conforming thing much quicker. If I want to lay on the firmer side I crawl over and can tell the difference immediately.
I still struggle with pillows. I can't find quite the right match to get me through the night. I hope that you won't have that problem. This is an ongoing struggle.
BUT the biggest thing (If you're still reading, you are smart) is that my husband has commented that I have NOT SNORED ONCE since I got this Serta mattress. Why? I don't know, I can't find the right pillow, so I can only say it is the memory foam base. I had a pillow top that cost over $3200 and I snored; but this mattress has made me so comfortable that my neck is not curled in such a way, and I've stopped. A month in...nope, no snoring yet (and I've even got a head cold this week).
Another thing I noticed immediately was I often woke with my shoulders in pain like I've shrugged them all night. Seriously, that was gone on the first morning and hasn't come back.
Yes it is firm, but it gives after a few minutes to be comfy, and just keeps getting better.