It's heavenly to lay down on when I'm exhausted but I've found that sleeping on it all night hurts my back because it's difficult to change positions.  However, this is due in part to our dog who insists on sleeping on it as well as the giant pile of blankets we use that block my movement.  Instead I put it on what we call "the living room bed" which is a twin mattress we plop down in front of the fireplace in the winter and that is truly the best spot on the planet.  Warm, soft and the perfect spot to watch tv.  If I were to buy again, I think the 3 inch foam might have been better to choose in order to get a bit more support from the hard mattress underneath while still cushioning pressure points for me; my hip bones and shoulders.  Another tip:  You might not need a pillow if you have this 4 inch topper on your bed.  I found I didn't as my body sunk into the foam just enough that my head was already perfectly supported.  Not recommended at all if you're a belly sleeper.