I stayed at Mario's place with a group of 6 friends and it was a great apartment for hosting a bigger group due to the large living area, separate bedrooms and individual bathrooms so that we could come together for breakfast and socializing but also have enough privacy. Mario was a very responsive host, check-in and out were super easy even with our very late arrival time and the apartment was clean and orderly. I really appreciated the app and map that he's made for his guests and would recommend you to also use it if you visit.
The downsides: the apartment is on a busy street so the traffic was quite loud. Most were disturbed from the noise so walk with ear-plugs. There were too little plates and bowls and tea-cups for the number of people and the kitchen was missing basic items like salt or sugar so we had to buy all those things. Maybe if you stay after us you'll benefit from those things :)
Overall, a great place for a group stay.