I often find sitting in/on it more comfortable than normal chairs. Either lie or sit... you soon get the hang of where to sit on it for maximum comfort. It is actually one of the best things I've ever bought. Careful when you get out though... the words 'beached' and 'whale' spring to mind.
It is pricey however... my wallet was cushioned ('scuse the pun) by a gift voucher but if you have the cash, buy it!