Excellent location, right in the center of London and within walking distance of Covent Garden, St. Paul's, etc. The Chancery Lane station is also only a good 5 minute walk from the apartment.
The building isn't the newest, but the room offers everything you need for a few days: decent bed, kitchenette, toilet, shower and even a tv.
On hot days, you can start to feel the room heating up in the course of the day, but luckily there are some very good, thick curtains to block out the sun. The area is relatively quiet at night, but if you close your windows, you won't be bothered by noise as they're pretty soundproof. The area also felt safe at night, nothing to worry about.
Finally, Mus was very responsive, friendly and was even nice enough to let me check in a few hours sooner, so I didn't have to drag my luggage around all day.
To sum up: great place (for a couple or single person) to spend a few days in London. Would definitely consider staying here on a next trip!