The Serta iComfort Blue 100 CT Gentle Firm mattress is great! I was a little hesitant about having a firm mattress but really needed better support than my existing plush mattress. I am so glad to have this mattress! Contrary to what I thought, this is a very comfortable mattress and is not rock hard at all. The top layer is soft but firm so your body comfortably rests on it without sinking in. I sleep on my back or on my side and have woken up in the morning without any back pain or muscle stiffness which is a great feeling. My old mattress was getting squeaky due to old inner springs and it’s such a relief to not have to worry about squeaky springs when you sit down or turn sides. I also have not felt like I was overheating at night so that’s another plus. The depth is a bit taller than my previous mattress and some of my less deep sheets don’t fit perfectly and you can see the mattress peeking out but that’s not a big deal. Overall this is one of the best mattresses I’ve owned!