The apartment is conveniently located, very close to the U-Bahn and with a large number of restaurants and convenience stores very close. Reasonably quiet for the centre of a city and large enough for a stay wit several people (would not recommend for more then 4 adults though). It is mostly clean, but both the kitchen and the bathroom are a little dodgy in their appearance.
Some minor details: the kitchen is well equipped (including a nice coffee machine!) but not very practical, and there are no kitchen towels (asked for them and the reply was: we don't provide kitchen towels - well, how do you wash up then?). The bathroom is quite tiny with only a small hand-washbasin and the toilet is very crammed in between the basin and the shower, with a wall in front. Not a problem for some days, but for longer stays there are -I think- better options in Berlin.