My stay at Lena's flat was perfect. The apartment is wonderful, very spacious and comfortable. It is full of light and beautiful plants. The bedroom has a very big and super comfortable bed, and a little terrace in a balcony where you can have breakfast in the sun. The kitchen is just lovely, and so is the living room, very big, with two big tables where you can even work. Everything was perfectly clean and tidy, and you feel really at home there!
The house is very well located, just next to U-Bahn (dirct line to Friedrichstrasse) and tram. The area is full of little shops, cafes, pharmacies, supermarkets, etc., and also very quiet and safe, even if you come back late at night. There is a park nearby (with open air cinema!) and a beautiful lake where I used to go to swim and sunbathe, just two tram stops away!
The contact with Lena was very easy and she is very friendly. For all thereasons above, I totally recommend this apartment, and for sure I would repeat in the future. :)