My wife had back pain everyday with our old mattress. With this new Ghostbed, her back pain is completely gone. She gives a 5 star rating. 
I give a 4 star rating because I don’t feel any “cooling” on the mattress once we put sheets on the mattress. Without sheets, I do feel the cooling feature of the mattress, but it’s not really practical to sleep with no sheets. That said, I don’t have any other experience on a different memory foam mattress, so it may be cooler than others. 
As for the rest of the mattress, I agree with a prior review. It feels like a slab of concrete when i first laid on it, but I feel that I subtly sink in a little during the night. It took me a week or so, but I sleep very well on this mattress.