Our stay was amazing!
The toilets and bathrooms are shared but are new and super clean. Showers' stream power is strong, and there is always hot water. There are two kitchens, well equipped and comfortable.
The rooms are sufficiently soundproof, the beds are comfi - and there is a private fridge inside the bedroom, which was very convenient.
Excellent WIFI.
The location is great! 10 meters from the metro station of the circle and "hammersmith & city" lines, and 2 minutes walk from "Bakerloo" line (Which the latter reaches Piccadilly center, the West-End shows, and china-town area). Just next to the metro there is a Mark & Spancer branch (A more fancy supermarket, and yet not that expansive) and there is a tesco-express within a five minutes walk. The building is located within a walking distance of Hyde Park. The Baker-Street station to (and from) Luton Airport is located within 10 minutes walk (with luggage).
Check-in is very easy, and communication with Marcelo, or Lisa, was fast and useful.
I would definitely come back the next time in London!