Amazing location! You are a short walk away from the main train station, museums, restaurants, shopping, and great sites. While there aren't multiple separate bedrooms, the space is big enough that you have separate sleeping spaces.
Marc was very responsive and usually got back to me within minutes. He also let us check in early on the first day, which was super nice.
Two small negatives: 1) People often smoke in the stairwell and the smoke drifts up the stairwell and into the apartment. Admittedly, I am very sensitive to smoke and not used to how prevalent it is in Germany; 2) I wouldn't describe the furnishings or linens as luxurious.
All in all, I'd still highly recommend Marc's place. Thanks!