Your '13 Discovery should give you good service provided the previous owner did the routine maintenance. The chassis and drive train are built to last and will if properly maintained, but the house stuff not so much. At nearly 6 years old, in the coming years you can expect to repair air conditioner, steps, furnace, replace tires, replace batteries, and a bunch of other stuff I can't think of right now.
But this is true of any motor home. If you like the floor plan and the coach passes inspection, you've done you're due diligence.
'07 American Tradition 40Z Cummins 400 ISL
Towing a '14 Honda CRV