I bought a Davidson Perfect Sleeper by Serta and it is the worst bed I have ever slept in in my entire 65 years.

After 6 years of nagging back pain from sleeping in a hole on my Serta Not-so-perfect Sleeper---this mattress has NO recovery when you change position I finally I got the great idea of flipping it over and sleeping on the bottom of it. I bought two foam toppers, a memory foam, and an egg crate and it is actually better than sleeping on the pillowtop and my back is so much better after just 2 weeks. As soon as I can afford to, I will replace this bomb of a mattress.

I've had this mattress for 3 years now.
It's the best mattress I've ever had, but I must also add that I've only had 3 mattresses.

My old mattresses were:
-An old flippable Twin when I was 6-18 years old. It was my dad's when he was a kid, so it was pretty worn out by the time I got a new one. I woke up with back pain almost every day my last 3 years in it.
-A new flippable Full from 18-28 years old. At the time, I thought it was great. I only woke up with back pain a couple times a week.

I went to a mattress store looking for a queen after I got married. We saw this one on sale for $400. We tried it out in the store and fell in love with it. I bought the "plush queen" version. We tried the pillowtop but didn't get it because we figured the pillowtop would compress like pillows do.

For the first year or so, it was fantastic. My back pain was gone, and it was incredibly comfortable. I could fall asleep instantly.
After 2 years, I started having back pain again. After 3 years it has a pretty noticeable sag. I haven't measured, but it's very noticeable when looking at it. My dog does lay on it during the day, but she's only 60 pounds so she's not contributing to the sag very much.

It is clear that Serta designed this mattress to feel great in the short-term(in the stores), but it is not built to last. That said, it is at a very reasonable price.