Any RV needs maintenance (including the occasional repair), and generally speaking older ones do need a little more maintenance than newer ones...but many tasks apply to all.
As others have said, condition is far more important than outright age. There are a few things that wear out and need replacement just due to age, such as tires and LP/CO/smoke detectors, but they're the exceptions rather than the rule. I'd rather have a twelve year old RV that's been well cared for than a three year old one that's been neglected.