Soapbox, my DS1 (aged 6), moaned and moaned at me to buy this when my Mum sent some money. I didn't want him to have it, for a couple of reasons, felt it was a gimmick and he would be fed up of it, especially if he couldn't get it to work properly, he would also probably just press the buttons continuously which would no doubt make a noise and wear down the batteries (fed up of toys that need new batteries), also he had just spent almost £10 on a new money box a couple of weeks previous.
Don't know if not buying it was the right thing to do, it certainly had appeal for my 6 year old, he went on and on about it but I wasn't fussed as a Mum.