We had a great time in this apartment overall. The host is very responsive, and we found a clean, nicely set up apartment, in a good location (there's a supermarket and a cafe 2 min away, and it's close to a subway station as well).
One thing to note for very large groups: while it can certainly accommodate many people (we were a group of 16), the rooms do get a bit cramped once all beds are out (extra beds can be found under the main ones). There are also only 2 bathrooms - which for a very large group can be an issue. We spent most of the time outside of the apartment or in the living room, which could actually accommodate all of us on very comfortable couches (and a few extra chairs), so it wasn't an issue.