Absolutely recommended.
The apartment is perfectly located near the Savignyplatz, with plenty of restaurants, bars and entertainment venues only a few minutes away on foot. There are plenty of excellent transport options nearby, with two S-Bahn stations both a 10 minute walk away (Savignyplatz and Charlottenburg) and the U7 on Wilmersdorfer Straße just around the corner.
The building is a lovely and perfectly maintained Altbau, typical of old Berlin. The apartment itself is very spacious and is also perfectly maintained and tastefully decorated. Also, being in the courtyard in an already very quiet neighbourhood, there is absolutely no noise at night.
The only drawback is the lack of natural light, although this can be a benefit on hot summer days when the place remains nice and cool.
I stayed there for three months and I was completely satisfied. Sabine and Sebastien are fantastic and very friendly hosts, always willing to help with anything and making sure one feels immediately at home.