I have spent 3 days staying in one of the rooms in John's house.
This room has been very comfortable, with a private bathroom and also has a small refrigerator that has been very comfortable. It appears to have been recently restored.
It also has a common area, a large kitchen where you can count on everything you need to cook whatever you want. It also has a microwave, a large refrigerator and gas burners and oven.
I have been almost always out of the house, returning only at night. For that reason I have met John only once. He has made himself available for me to call him anytime I might need him. But this has not been necessary since everything was very well indicated in his house.
The place where it is located is obviously an old workers' neighborhood from what I have read. In other words, it is not a "luxury residential" area, but it has seemed very quiet and safe at any time of the day.
Regarding transportation, my GoogleMap almost always indicated the option of taking bus 15 and then the red line. The last day I discovered that the "purple line train" is very close and in 11 minutes it can take you to the South Station.
I found a shopping center 10 minutes away on foot where you can find large Target supermarkets among others, with extended opening hours.
I recommend it to other potential guests who want to spend a few days in Boston, organizing themselves well with the purple line schedules to get around, or if you have a car, no problem getting around the area as well as easy to park.