Absolutely love the flex mattress, my husband who sleeps hot as the time s now cool in fact he put a cover on the other night - it shocked me as he usually sweats and complains about being hot - meantime I'm freezing.
He a has a lot of pain in his neck and back now he doesn't even notice that pain is gone in both his neck and back. Even after a long day mowing as we call it the back forty he gets up the next day. 
Me I just love our twin extra long mattresses, because of surgery I have to sleep sitting up and even that is more comfortable for me as I get the support of the individually wrapped coils but the cushiness of the top layer.
Obviously we are both in love with the mattresses.