I really enjoyed my stay at Mark's. It's within walking distance of Central station and of Harvard.
Mark sent detailed check-in instructions the morning of my check-in and meet me when I arrived. His place has all the mod cons and he's really thought of everything you might need. The apartment feels new, clean and very modern. I stayed in Room 4 with the en suite which has a bath and a shower. The neighbours upstairs unfortunately have creaky floorboards and sound like they walk elephants around up there but it didn't disturb my sleep and I had a lovely stay.
There are a couple of other rooms in the apartment where other airbnb guests stay which I hadn't realised (my mistake most probably!). I only saw and heard the others a few times and everyone was very pleasant and mostly kept to their rooms if they were in.
The app to lock the front door and my room door was easy to download, my old phone was just a bit temperamental when using it but there's always a backup physical key which I mostly used.
I'd definitely stay at Mark's again if I were in Boston :)