It is a great place stay for a family vacation. The location is excellent, walking distance to most of the attractions. Plaza de Espana is 5 mins, the Royal Palace is 15 mins, and etc.. It is also surprisingly quite given it is in the heart area of the city. The amenities are also abundant, washing machine, dish washer, counter top, and etc.. The beds are comfortable, even the sofabed is better than the ones from most of the hotels.
The host is very flexible in terms of check-in time. We arrived much earlier than the designated check-in time, and the host arrived immediately after us.
There are not many cons. One that many others have mentioned is that the stair case is very narrow. Carrying big luggages up and down can be difficult. Another con is the hot water heater is not very big. I'd say it can hold hot water for 3-4 people to shower normally. More people on top of that would have to wait for water to heat up again.