"Anna & Karina" are actually a company that rents all the apartments in the building.
Regardless of this detail, I stayed for one month in the apartment and I am very happy with my decision. The apartment was clean, it offered all the expected services that you may need during your stay, and the apartment was exactly as the picture shows.
The only downside, if I have to point something out, is that the apartment is quite far away from the city center, but public transportation in Zürich is excellent. Thankfully, there's a mall located very close (walking distance) to the apartment.