Love it. I just helped my son apply for his first credit card and as we were looking at the options I told him not to worry about which one had the best interest rate because if I ever caught him paying interest anyway there would be trouble
I told him to think of it as a "convenience card, not a credit card because he should not spend on it unless he already has the money to cover his purchase in his bank account.
Now, this only works currently because he is still at home with few expenses and we are his safety net but I have been drilling two things into him since he was a old enough to listen - "wrap that rascal" and never pay credit card interest.