I had a very nice stay at Celia/Jonathan's Brownstone penthouse. The place is immaculate, the bed is comfortable and the shower works. Jonathan met me as promised when I arrived, showed me around and gave me several tips for my stay. I was fortunate to also meet Celia (and her mother who was visiting) one evening. Everyone was pleasant and welcoming.
I stayed here on my own - a couple might find the apartment a bit on the small side, just given the sloping roofs but although I am reasonably tall, I was actually fine. I am a walker so I walked miles and also used the Boston trains/trolleys/commuter rail systems. It is a really easy city to find your way around once you get to grips with the public transport. I would happily stay at the Brownstone again.