Please expect this mattress to take about a day to fully inflate before you can use it and there will be a plastic/rubbery smell for a couple days; so leaving in an aerated room for a few days before using is advisable.

I was also surprised (not unpleasantly) that this mattress is firmer than I expected.  I am no lightweight and I didn't roll into the centre or sink into the mattress.  My only gripe is the mattress I got (king size) was slightly larger than the old king size mattress it replaced (about 1 inch); so I had to squeeze it into the frame a little.

That all said, this is a comfortable mattress and I no longer have uncomfortable springs poking me in the back.