I have one of these on our king size bed and it incredibly comfortable. We had to buy a very firm mattress because of hubby's weight and back problems. This topper adds the perfect amount of cushiness that we both love. Our son has one on his bed too. Loves it.
Bought it mm 3 months ago I say, expected the topper to be softer after some use - pretty firm still , regardless my cuality of sleep has improve since I got it.