The Tap Room at the Jared Coffin House is a cosy pub carved out of the Coffin House's basement. In the winter, it's popular with locals (though that may be in part because it's one of the few resturants that's open year-round).
On an island where eating is almost universally expensive, the Tap Room provides a good value--my friend and I had two beers, two steak dinners, two coffees and split a dessert. The steaks were tasty and perfectly cooked to order, the apple crisp a'la mode was warm and comforting with a crumbly strusel topping, and the total bill came to $55--not horrible in a town where a burger can easily top $9.
The decor tends to dark woods, with an overall colonial feel, and the staff is efficient and friendly.