The location in Berlin-Mitte is perfect, many sights are close by and good nightlife is in walking distance (Oranienburger Str., Hackescher Markt). The apartment is spacious and clean. Here ends the pro-list.
When we arrived on Fri evening, the hassle started as the person we called by mobile took about half an hour to organize the correct room key - this already shows how unorganized the place is. There are 4 rooms in the apt, how hard can it be to put tags with A, B, C, D on the keys? Then, she wanted money right away and it was agreed upon that we get 7 Euro down for the key hassle. The concept of getting a receipt as proof of payment was not understood, so I said OK, if I can get the receipt not until tomorrow morning from the manager, I'll pay then. No way, the "manager" Dirk was called. The immediate suggested solution to the problem was that we could simply leave - he obviously doesn't want you (but you are welcome to leave your money).
In the end, we ended up paying the next morning anyway to that "manager", who of course canceled the 7 Euro-deduction his worker agreed to the night before. It was also affirmative that there's no way to store our luggage after check-out on the day we leave. He told us that he himself traveled a lot and knew how things worked, period. Judging from his behavior, this can mean two things: A) He's simply lying, or B) he traveled and hasn't learned a thing. Because this is definitely NOT the way things run, wherever you go. Not being able to leave the luggage was a definite first for me, we had to use the expensive lockers at the station.
For that intolerant, unacceptable and small-minded wacko who calls himself "manager" I advise you to stay away from this place.