I brought my family down after reading a book about the real Moby Dick ship, The Essex, and was game to learn more about Nantucket history and present (for that contact the visitors center).
The Inn (or B&B as it might be known) is nice and cosy with a gas fireplace in the library (nice books) and eating area (nice continental breakfast). It's got a nice location, walkable from the ferries and very close to the whaling museum (closed January 4 to Feb 4 or so, take note!), lighthouse, Children's Beach. The innkeeper nicely offered suggestions on good nearby food and found a tour guide for a drive around the island (Sabra - good) and we also found you can get a walking tour (Bill-didn't try him) from the Visitor's Center on Federal St.
The building and rooms are nicely decorated and have thermostat powered electric heaters and also big heater/ac units. We were able to get blankets and there was an airbed that just fit in our room for my daughter. Walls on Nantucket are thin but the 7SI's walls were thick enough and we slept well and don't think we disturbed others either. There were more than enough TV channels, hot drinks available anytime (from the common area) and a fridge where food could be saved. There is a widow's walk with ladder entry which my daughter and I climbed up (not for the unfit, but worth doing during day if you're not drunk and not a clutz). I booked directly with the owner for a good winter price. I think the owner said that they can accomodate a total of 26. This Inn makes a great place to stay off season and I'd assume any time of year.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC