This apartment is in a great location, clean, and very spacious. It is across the street from Rathaus metro station and from a trolley line and about 3-4 blocks from museum quarter. We were able to get to city center/opera house in less than 15 minutes by metro and about 30-35 minutes walking at a comfortable pace and stopping frequently to take pictures.
The apartment itself is huge and was comfortable and roomy for three of us. I feel like it would be comfortable still for about 6-7 people total since it has a very open floor plan with three distinct areas which are separated by doors. It has a kitchenette area with basic cooking utensils, plates, pans, etc and a small fridge. The apartment does face the street so you do get some traffic noise but we thought it was tolerable since it dies down significantly at night. It is a pretty quiet street at night, in a very safe area, so you do not get the noise from rowdy pedestrians at night.
Two things to be aware of: 1. the metro line does run under this intersection so at times you do feel a little shaking. We noticed it the first day but got used to it so it was not a problem for us at all. I can see though see how this might affect someone who is a light sleeper. 2. There are two wifi networks in the apartment but although they are functional they are weak and sometimes slow compared to what I'm used to.
Overall, this place is great. I would recommend it and i would definitely stay there again. Vedi and Cristoph are very nice people, responsive, and were flexible with setting our check-in time.