Exterior Stained DoorsStained doors can stay looking great for years with the right annual maintenance. This door sits back and is protected from weather and sun also is facing north. This is the perfect situation for a stained/varnished finish on the exterior.
If this door was flush with the front wall being unprotected and facing south into the sun without shade you may have to revarnish two to three times a year and still the door won't last as long as the one in the picture. It's mostly the ultraviolent rays that break down the clear coats.
The best clear coats out there today won't last long in direct sunlight. Consider the sun and weather when deciding what finish to apply to that new front door. Sometimes a nice paint job/color is best over stain/varnish.