Couldn't sleep more than 6 hours on our old mattress without waking up with back pain. The first night I slept 7 hours and woke up feeling great, and it's only getting better.
It's a comfortable mattress and I'm glad it's made out of safer products, but it's not as amazing as I expected after reading reviews. It's still a good mattress though. I have noticed that it's breaking down a little on the edge of the mattress already too.