Bubber - is it great or waste of money?

[Mummyyyyyyyyyy]

Hi, my 10 year old has asked Father Christmas for some 'bubber' a kind of modelling clay that doesn't dry out. I've only seen it for sale on amazon (£10 tub) & very few reviews. Has anyone bought any of this stuff? If so was it hours of fun or a 2 minute wonder that's squashed into the carpet by Boxing Day?
Many thanks.