Three of my friends and I stayed in Dan's apartment during our time in Vienna. We were very grateful for the wonderful location; during our whole stay there was no need to take the subway (except going to and from the train station) because everything was walkable, with the main attractions no more than a 15-minute walk away. We slept with two people on the main bed and two on the fold-out, and the fold-out was a bit stiff, but the main bed was perfectly comfortable. There's a small kitchen area where you could make some coffee and it's stocked with glasses and utensils that you might need. Everything was clean and well-organized, and the building felt safe. We didn't interact with Dan very much, but he reached out to us to make sure that we had gotten in okay and brought us the sheets for the fold-out. Overall, we had a nice experience in Dan's apartment. We were out during the entire day for our whole stay and only spent time in the apartment at night, but it had everything we needed and was comfortable.