I've stayed at Petra's house for two months during my traineeship. On the first month everything was fine and Petra was nice to me, but after I paid the second installment she started complaining about everything I did. There are several rules that guests at her house must respect, but the first who does not respect them is Petra herself and each time I've pointed it out, she's made different excuses.
Television in the bedroom does not work and wifi is pretty slow.
On the other hand, the apartment is strategically located 2 minutes walk from the SBahn station Hohenzollerndamm and in just 25 minutes you arrive to Friedrichstraße. Nontheless I don't find that this apartment is worth the sum I've paid.