I found this mattress to be extremely firm, maybe a bit too firm.  Laying on it for the first time felt uncomfortable at first, but after about 10 minutes, it made my back feel better.  The problem then was laying on my side or stomach (I am mostly a stomach sleeper).  I felt this was too firm for that and it actually made my hip hurt on my side.  However, I solved this problem with a mattress topper.  Once adding the topper, it gave it the perfect comfort to lay in any position.  I definitely noticed a big different one the first night of sleeping on my stomach.  The firmness of the mattress did not allow for my back to arch like it usually does and I woke feeling so much better.  I am extremely pleased with this mattress after being very fearful that I would not sleep better than I had on my previous mattress.