It's basic, clean, and accurate accommodations for people who are planning to spend their days in London OUTSIDE of the apartment. I don't mean this as a bad thing at all. They also spruce up your apartment every few days (new towels, fixing your bedding, etc).
It's 10 minute walk to a train stop (Baker Street and Marble Arch stops), and there are buses up and down the street where the apartment lives. You are central (Marylebone area), but it's also quiet at night to sleep.
The people who work there are nice and pleasant, and the person responding to inquiries over the Airbnb messaging system is responsive to your questions.
There are no lifts to any of the upstairs apartments and no central A/C (but it wasn't that hot when I travelled this summer) so keep that in mind if you need accessibility in that regard. The walls are also kind of thin so if you have noisy Airbnb neighbors, that can be a problem, but I was fine.