Anytime someone offers me a zero percent finance offer, I'm pretty much taking it.
Beyond big things - homes, cars - I don't buy things I can't really afford. But if I can spread payments out over 6-12 months and invest my money elsewhere over that time, well, that just makes good financial sense.
For example, earlier this year, I bought a bunch of weights and lifting gear. They offered 12 months same as cash. The monthly payment was about three times my monthly gym membership. Once I had the gear, I cancelled my gym membership. So really, it cost me very little each month for the year to have my own weight gear, and after three years, it will start paying for itself since I will not be paying the gym membership.