I bought a Queen size one of these mattresses for my motorhome, it has been great. BUT, this King I just got for home, well, the end that was on the outside of the roll-up has not expanded, It has been two weeks and it appears it is not going to. The entire rest of the mattress went to 12", but this end in the picture got only to 10" and the corners are just squashed at 8". Weird.
As for comfort, it is what I expected, a bit softer than the queen I bought, even though the description called it "Firm to Medium". I think that is due to the added thickness, the queen was only a 10".
UPDATE 12/30
OK. I am now back in the motorhome, sleeping on the queen. The king and queen are COMPLETELY different. The queen is firm, the king is soft, not medium but soft as other reviewers have said. Wish I could send it back, but that is the rub. If I had paid $1000 local, I could, but here I am stuck with it.
I did notice they have added a note at the end of the description "Please be advised that even similar products may produce different firmness results."
THAT IS FOR D@$% SURE