Stayed here on my recent trip to Zurich. The size of the apartment is quite impressive. Large kitchen and a nice cozy living room to relax and watch movies in. As others have noted, this unit is right next to the highway, so there is a bit of noise from the road, but honestly in my opinion, when you close all the windows, it is very quiet and you can barely notice the highway noise. So, not really a big deal for me. Just a fair warning to anyone considering this location though, this building is shared with an orthodox Jewish community and they use the lower floors. There is quite a bit of noise from them. Loud thumping, very loud vibrating noise. I suspect this is from laundry being washed downstairs, not sure. Most of the noise stopped by midnight, so it wasn't too big of a deal, and I was able to sleep, but definitely something to consider when looking at this place.
Location was great as it was only a 5min walk to the nearest public transport. We had no issues getting around. Neighborhood was quiet with nice little shops to check out as well.
Kitchen is large, but lacking some basic equipment, so keep in mind if you want to cook. I had to buy some equipment from the store just to cook a proper meal. Stove top only had two functioning burners out of the four. Coffee machine was broken, but my girlfriend and I are low maintenance and not bothered by this kind of stuff. We made dinner with just the two burners, and coffee was made with the electric kettle, a strainer and a paper towel and just cutting open the coffee pods. A little extra work, but nothing too bad. Still able to enjoy coffee in the morning.
Overall, fairly positive stay here. I think a 4 out of 5 star rating is fair.