We stayed at Olga's place for a weekend with 3 other friends. The appartment is a bit too tiny for 4 adults (one had to sleep in the sofa bed and one in the kid's bed, which is, well, made for a kid) so I would recommand it for a couple and a kid but not 4 adults. Otherwise, we didn't stay much in and had a great time in amsterdam, the place is easy to get to from the station and the city center by just walking. The backyard is a nice thing to have too. Also, Olga was very friendly and easy to communicate with, she made everything to make the stay easy for us, for instance, she let us check out late in the afternoon which was great!