Bank or Car yard finance?

I have just purchased a second hand car from a large dealership.I have been approved a loan through my bank with an interest rate of 13.7% fixed for 7 years unsecured.I have also been offered finance through the car yard for 10% fixed for 5 years secured.I have heared car yard finance is dodgy even though the deal through the car yard is alot cheaper than the bank.Has anyone got finance with a car yard if so is it a rip off & how do you find it as opposed to bank finance?