My partner and I stayed at Heidi's place for 4 nights in August 2019. Heidi was an awesome host and responded very quickly to our messages! The location was fantastic, probably 5min walk to Potsdamer Platz but still walkable distance to to other sites (~25min to the Reichstag, or Checkpoint Charlie). Guests who are looking to do substantial cooking might have problems as there is no kitchen sink (just the bathroom) or any appliances beyond the microwave and mini fridge. The apartment was huge for a studio, but was quite warm while we were there in a small heat wave (daily high of ~33C). We would recommend staying at Heidi's place.