This is a firm gel/foam mattress, there is a bit of your body sinking into the mattress but that's normal for gel foam. You could slept in all possible positions and I slept great.
One big problem with many new-style no-flip mattresses is that they are too tall, so when you put them on a box-spring and frame, the bed will be too tall. But with a platform bed and this mattress, the height from the floor will be exactly right.
The sheets stay on the bed pretty well and it's good pros to be able to lift it with one hand easily to make the bed or move it. When one person moves, the whole mattress doesn't shake. The washable cover is a nice addition also.
And with a 25 year warranty, you just can't see how one could go wrong! Also a plus that it will come in a manageable box, so you could dolly it in the house, unbox it and put it on your bed frame, no problem!
So, if you are looking for a soft cool mattress this might just be the one.
Customer from amazon reports that this mattress did not hold up at all. After owning for four months, he noticed that the bottom was damp and upon further inspection had black mold. So it could be the gel/materials in the mattress.
Overall, this mattress have over 91% positive reports from satisfied buyers. So make your choice with your head.