This mattress is a good firm one. It's not overly-firm, though. I didn't notice any chemical smell when it arrived. We slept on it the first night, and it reached its full size by the next night. I used to be jarred awake when my husband came to bed or if one of the cats jumped on the bed, but now I hardly feel it when my husband lays down and I don't feel a thing when the cat jumps on it.