I got this last-minute for a guest who was coming in to stay with us (Used with the AlwaysCool 8" Innerspring - you can see where my concerns lie). It only took about 12 hours to inflate fully, but we kept it out to expand for at least 24 just to be sure. Our guest basically wrote the review for me when she woke up. She raved, and said it was firm, but plush - perfect for her. It was a cold night, so no word on the promised cooling capabilities. Either way, I'm excited for a chance to sleep on it myself!