We had a pleasure of staying at Juan's Carlos apartment during last April. The apartment is fully renovated and feels totally new, to my opinion the interior is nicely picked as well. It really felt to be at home away from home.
The location was great- just 5 minutes walking from Plaza Espania, 2 minutes from the nearest subway and close to a very nice bars and restaurants (which felt more local and less touristic which is a compliment).
So, indeed the place is fully recommended by us.