This is where you can find Uncle Ken during the Far Harbor quest “The Hold Out”. If you visit the area before accepting the quest, the place will be empty. Inside the gift shop, there's an Islander’s Almanac on the counter, ground floor.
You can also find a Green “Vim”-painted T-51 power armor, north of the center, inside the Vim advertisement truck along the main road.
The barricaded area is small but the settlement's territory extends up to the parking lot and the empty lot behind the building. You don't need to extend your defenses outside unless you have a lot of spare resources to build ample defenses. The hedges in the parking area provide natural protection so avoid scrapping them.