Just returned from a week in Boston, staying at Atef's studio. The studio was exactly as described, entry is via the courtyard garden at the back of the house (access via a private alleyway at the side of the house). The studio was clean and comfortable and certainly large enough for one person. There is a cooker (which I didn't use), refrigerator and microwave (which I did use!) as well as a range of kitchen implements. Lots of storage space and a comfy sofa to sit on. Access to the laundry facilities was very useful (and it's just outside the door so handy too!). WiFi availability was a great bonus. The studio is at basement level, and 2 of the windows (glass blocks rather than traditional windows) are at pavement (sidewalk) level on the street. Despite this, it was very quiet, there was very little traffic or other noise from outdoors.

The location of the studio is very central, and is within walking distance of downtown Boston and other sights - less than 10 minutes to the nearest T stop, approx 10 minutes walk to North Station for trains to Salem & Gloucester. Charlestown itself is lovely, it was very safe and comfortable to walk round (important for a single traveller like myself!). Bunker Hill monument is at the top of the street - a great landmark so you won't get lost!

I met Atef (and Lulu the cat) when I arrived, and both of them made me feel very welcome. I had no problems with the doors (which another reviewer commented on). The courtyard garden looked very nice, I didn't use it myself, although guests are free to use it if they wish.
This was my first AirBnB experience, and I was delighted with the result.
Now where to next?!!