We had an excellent experience in this appartment. It is all about location location location and this appartment is just that. Walking distance to sites, restaurants, shopping and public transport (metro/bus).
We have some experience with staying in airbnb appartments in Madrid and it was nice to have an elevator in the building as the appartment is on the 4th floor.
With the entrance to the building on a busy street (only with human traffic though) the appartment is surprisingly quiet!
Don't forget to have a look at the ancient wall on the ground floor!