I stayed at Sevis place for the duration of two weeks (22nd July - 3rd August), and as such feel like I have seen and lived most aspects of the place.
To start off with, both hosts are really nice and welcoming. You'll run a higher chance of running into Asla (the female host) than into Sevi (the male host), if company is what you are looking for.
As the description mentions, the place is situated in the 'Langstrasse', which is not only a street filled with clubs and bars but also the old red-light district. Although prostitution as such is forbidden, the street is still filled with mostly female prostitutes at all hours.
Something else that might be of concern for the occasional AirBnB guest is the noise, which does not only persist on weekends as mentioned in the description, but throughout the entire week. So if your are looking for a place to get a solid nights sleep, this is not one I would recommend. (As a heavy sleeper and wearing earplugs, I would still wake up several times during the night)
Privacy (for me personally) was also an issue. I usually left to work early in the mornings having left my window open to air my room, only to come back at night finding it closed with the blinds down. As a paying guest, I would expect no-one to go into my room whilst I'm away. (there is no key to lock your door)
All in all you get what you pay for though, and these are just a few small standouts I would have liked for someone else to have voiced before I had chosen this place.
Nevertheless, the cleanliness is pretty much top notch 9/10, the bathroom and toilet are all that you could ask for (10/10) and the kitchen has everything you need (10/10).
Finally, if you are looking for a one- or two-night stay in Zurich, noise doesn't disturb you and sleep can wait, go for it!
If however you need to be on your A game in the morning and you're easily disturbed by noise, I'd suggest to look for a calmer stay.