Heinz's place was exactly as promised: a spacious, clean flat in a perfect location for sightseeing. Communication was great and we had no problem finding the place. There was a brief miscommunication when we arrived and were told we wouldn't have access to the baby crib we had asked for, but after a few minutes two employees ran out and grabbed one for us. The beds were the most uncomfortable we had all trip, but I think we were too tired to care.
The building and parking lot has its own interesting history: it's built on the site of the former Führerbunker, and there's a sign at the entrance of the parking lot explaining its history.
Would definitely book again.