I bought this as a topper for my boyfriend's lousy mattress, since the reviews were good (and the topper reviews were pretty mixed). I was concerned about three things: smell, firmness, and heat retention. No smell at all, although we let it air out for two days before putting on the bed. I'm used to a very firm innerspring mattress and this is definitely a different feel - soft and firm at the same time. Firm enough sleeping on my back but I do sink into it when sitting, or laying on my side. As to it being hot to sleep on - I have to say I haven't noticed any difference. It's a vast improvement - no more aches and pains in the morning! We both like it. I only sleep on it on weekends though and now that I've tried foam I probably wouldn't choose a foam mattress for full time use.