Stayed here for 3 nights at the start of September last year. The house is amazing - full of history and lovingly decorated with furnishings in keeping with the age of the property. It is situated next to the Mayflower Society building, minutes from the Rock and the main street of shops and cafes, and about a 15 minute walk from the harbour. Hostess Barbara went out of her way to make us feel welcome - the breakfasts were amazing - Something different every day!
The only thing I would say is that Plymouth is a very small town (in american terms), and the public transport is practically non-existant so you definitely need a car to get about. We got the train down from Boston, and the station is a good couple of miles from the town centre of Plymouth. The bus runs pretty much whenever it wants, and only old people really get it - everyone else has a car. Even the people in the tourist information office in Plymouth were unable to read the timetable!! we ended up walking the 3 miles out to Plimoth Plantation (although everyone thought we were mad!) and though we managed to get the bus back (and it is a straight road from the plantation to the centre of town), we had to change buses at a layby on the freeway just outside Plymouth in order to get back to the town centre. We also arrived the day after labor day (september 6th), so it was very very quiet and pretty much everything was reverting back to winter opening hours, and a lot of the ferry services and whale watching/fishing tours had stopped.