The apartment is large and a good size for groups (we had three couples staying). The living and dining rooms are spacious too - but the black chairs aren't particularly comfortable for watching TV / movie - and the sofa only fits three people. The bathroom is nice and big, with both a shower and bath, but the water pressure wasn't great and we had a few issues keeping the temperature constant. The rooms were all nice and big - but the curtains do not completely cover the windows (not a huge issue for us given it was winter) - and some of the pillows weren't great (they were incredibly big / poofy, so it was like sleeping on a mountain).
We found the check process to be easy, loved the beautiful building and the neighbourhood. There were lots of good quality cafes nearby - and only a short walk from museums and city highlights.
We did enjoy our stay at the apartment, but I think a few small improvements would really make it a 10/10 stay.