I've had app errors twice when trying to post to the General section (hence the two empty threads from me), so let's try here an see if I have any luck.
I've had two from Argos - got them about a year apart and interestingly the older one now takes less air to fill up (i.e. make firm). Which is good cause it's easy to sit on - important given that I use it in place of a chair at work.
Been sitting on it 8+hours a day since sometime last year without a problem.