This mattress is great! Originally, I was going to purchase the most firm mattress and after reading other reviews, and I am happy that I choose the "soft" mattress. This is for my son who is 17 years old and a thin built person. This 'soft' mattress is plenty firm for him! Once it arrived, I unwrapped it and placed it on top of the box spring from the old mattress set. The mattress sprang open to life within just a few minutes and there was no smell whatsoever. I also read someone's review that said something about the outer box not being marked with the mattress size, but this box WAS marked. My son's old spring mattress was like sleeping in 'holes' and he could not get a decent night's sleep on it, and after just a few nights he has said that he has been sleeping well and it feels wonderful. When they say 11 inches, it IS 11 inches thick, which is thicker than the old spring mattress. I am one of those people who needs luxury bedding (awesome pillows, high thread counts, etc) to sleep well and I tried this myself and love it! Not one complaint and I would definitely recommend this mattress to anyone!!