We had a great stay in this apartment, lovely area and right in front of Retiro park.
Bear in mind, if you arrive after 8pm you have to collect the keys yourself at a lockbox in a different area. This is ok but it would have been nice if it was a little closer to the apartment :)
The place is really nice and clean, but you can hear the neighbors a bit though so bring earplugs if you are a light sleeper. Would stay here again.