The studio was as described. It is a great space with a lot of character, very clean and nothing is missing. The location is good and safe, including for single travellers, not far from the city centre. Yvonne and her husband are charming people and they are very accommodating.
The only issue I had was that the front door did not lock (you could open the apartment just by pushing the door), and as the room is on the ground floor, this was a massive issue for me.
I wish I had been informed of this before my stay, and that I had been given the opportunity to cancel, which I would have done as I did not feel that my stuff were safely stored when I went out.
Provided the lock is repaired, I consider the room a very good option when visiting Berlin.