Marie's flat is very nice, and I would highly recommend it if you're staying for a couple of nights in Zurich. Marie and her cousin are super friendly, too, which makes the experience even nicer!
All in all, it's a very nice appartment and vibe, but there are just maybe two things that should be noted: one is that when the flat is fully booked, you might be sharing the bathroom with 4 other people (which actually never turned out to be a problem for me, I have to say!). The other is that the room is a little noisy because the window opens directly towards the street -- so that in the summer it might get a little hot if you have to keep the window closed. But on the other hand, the view is incredible!
But again, I very much recommend staying at Marie's!