I stayed at the place with 9 other girls and the flat is really nice and spacious. We especially liked the big kitchen table, where we could sit together. The bedrooms were a nice size as well. The location of the flat was perfect for us. The only downside: it was REALLY cold, especially the floor and in the small bathroom. The flat had small portable radiators to plug in, but they did not warm the rooms.
Overall, our stay was really nice and I would book the apartment again, if I ever come back to Stockholm with such a big group.