Mark's place was just as advertised! It was clean and neat, and my room (Room 3) was spacious and bright. There are 1 1/2 baths, so even though there were other folks staying that weekend, there was never a bathroom conflict or anything. I didn't use the kitchen, but it's quite stylish.
There's also a TV in the room, and Mark provided a towel, all bed linens, and pump soap and shampoo for the shower.
I was attending a writer's conference at MIT, and I didn't mind the walk (about 30 minutes) to MIT each morning. The area around Mark's place is quite pretty, with some hidden gems (a "Hobbit" house, a little Indian restaurant, a business with a cool robot by the front door, etc).
Mark was very helpful when I asked about catching an Uber in the middle of the night (to catch my flight), and I really appreciated that.
If I attend the conference again, I would strongly consider staying here again!