You're buying a quality device that has been checked and tested by the company that makes and sells those very devices to make sure it functions correctly.
Personally I think they are excellent value but of course this is only my opinion and your mileage may vary.
Yes you can probably dig up stories of folks who have bought a refurbished device that does not function correctly but the same could be said for iPhones, android devices, automobiles and every single other object that could be sold second-hand.
Your choice.