Apartament is very nice, probably a former commercial space converted into living. It is ideal for a family (even a large one like mine) or a group of very close friends because spaces like bathroom are shared and there is little privacy. Dining room has a big table, beds are comfortable and architecure is simple, but cool.
Location's convenient thanks to 2 S-Bahn stations nearby (litterally 3 minutes walking), making every point of Berlin no longer than 15-20 minutes away. Is in a surrounding with high concentration of non-German people, adding some flavour of "real city" rather than tourist trap in my opinion. It is very quiet and looked very safe, anyway.
Minus point for the cleanliness: nothing dramatic, but it could be cared better.