I'm one of those people. I don't understand how it could save money overall - the finance companies wouldn't be in business otherwise?! - unless you are heavily involved in investing any spare cash you have and getting a big return, which is greater than the fees for the finance.
I also am of the loose opinion that borrowing is what's f**ked the world over (granted there are times when it's necessary and can be 'done properly'), but the amount of greedy credit companies and spackers willing to take them up on their ridiculous offers knowing full well they can't pay them back has made a mess. Oh and governments, how can a country rack up 1.15 trillion pounds of debt? Ridiculous.