The location of the flat was fantastic and within walking distance of all the main attractions within the center of Zurich. The flat was clean when we arrived and well-furnished. The bathroom was particularly good and spacious by European standards (the shower was also very good).
The bedrooms were okay however, the second one was a sofa bed which was rather uncomfortable to sleep on. There were no ceiling lights in the bedrooms and the one in the living area didn't work when we arrived (however, this was promptly fixed). The kitchen was modern, however it was completely empty when we arrive and essentially no amenities were provided (even the salt shaker was empty). The case was the same for the bathroom, where the shower gel in the shower was also empty. The internet was reasonable, however it dropped out intermittently and was by no means reliable throughout the stay.
As for the building itself, the apartment is located above a bar. The noise from the bar was not an issue and we barely heard it at all. However, when entering the apartment, you have to walk past the public toilets and cigarette machine of the bar which left an unpleasant odor in the hallway below. Whilst the noise from the bar was not an issue, unfortunately the noise from the apartment above was quite severe. The sounds of people walking on the floor echoed loudly into our apartment and the ceiling creaked throughout the night which made it difficult to sleep. Obviously, this is not the fault of the owner, but it became unbearable by the end of the stay as it was nearly constant during the night. All in all, the stay was fairly reasonable and could have been much better if a bit more thought was put into the amenities provided.