Overall, we enjoyed our stay at Bruno's apartment. Since we got in touch Bruno was very responsive and easy to communicate with. He agreed for an early check-in for us without any additional fee. That was really nice of him.
Regarding the apartment itself it was well equipped, WIFI connection was stable, it was warm and cosy inside (we were staying in the beginning of December).
The apartment neighbourhood is really vibrant with lots of good cafes and restaurants. In 20 minutes by foot you can easily get to the centre of Berlin.
So, to sum up, Bruno's place is a great choice for seeing Berlin and I can confidently recommend it to everyone!