we were 8 people and the place was up to the expectations. The two rooms are spacious and the 2 bathrooms definitively help to get everyone ready when you are too many.
Marco is very friendly and gives clear instruction of everything. Also the mobile wifi he offer (for extra cost) is worth it since you can carry it all the time with you.
The apartment is very clean and well located. I would definitively recommend it to anyone wanting to visit Rome.